diff --git a/python/damask/_grid.py b/python/damask/_grid.py
index eefd1e0be..94f7eefd0 100644
--- a/python/damask/_grid.py
+++ b/python/damask/_grid.py
@@ -4,7 +4,7 @@ import warnings
 import multiprocessing as mp
 from functools import partial
 import typing
-from typing import Union, Optional, TextIO, List, Sequence
+from typing import Union, Optional, TextIO, List, Sequence, Literal
 from pathlib import Path
 
 import numpy as np
@@ -70,7 +70,7 @@ class Grid:
               ])
 
 
-    def __copy__(self) -> "Grid":
+    def __copy__(self) -> 'Grid':
         """Create deep copy."""
         return copy.deepcopy(self)
 
@@ -161,7 +161,7 @@ class Grid:
 
 
     @staticmethod
-    def load(fname: Union[str, Path]) -> "Grid":
+    def load(fname: Union[str, Path]) -> 'Grid':
         """
         Load from VTK image data file.
 
@@ -190,7 +190,7 @@ class Grid:
 
     @typing. no_type_check
     @staticmethod
-    def load_ASCII(fname)-> "Grid":
+    def load_ASCII(fname)-> 'Grid':
         """
         Load from geom file.
 
@@ -264,7 +264,7 @@ class Grid:
 
 
     @staticmethod
-    def load_Neper(fname: Union[str, Path]) -> "Grid":
+    def load_Neper(fname: Union[str, Path]) -> 'Grid':
         """
         Load from Neper VTK file.
 
@@ -279,7 +279,7 @@ class Grid:
             Grid-based geometry from file.
 
         """
-        v = VTK.load(fname,'vtkImageData')
+        v = VTK.load(fname,'ImageData')
         cells = np.array(v.vtk_data.GetDimensions())-1
         bbox  = np.array(v.vtk_data.GetBounds()).reshape(3,2).T
 
@@ -292,7 +292,7 @@ class Grid:
     def load_DREAM3D(fname: Union[str, Path],
                      feature_IDs: str = None, cell_data: str = None,
                      phases: str = 'Phases', Euler_angles: str = 'EulerAngles',
-                     base_group: str = None) -> "Grid":
+                     base_group: str = None) -> 'Grid':
         """
         Load DREAM.3D (HDF5) file.
 
@@ -354,7 +354,7 @@ class Grid:
     @staticmethod
     def from_table(table: Table,
                    coordinates: str,
-                   labels: Union[str, Sequence[str]]) -> "Grid":
+                   labels: Union[str, Sequence[str]]) -> 'Grid':
         """
         Create grid from ASCII table.
 
@@ -422,6 +422,7 @@ class Grid:
             Grid-based geometry from tessellation.
 
         """
+        weights_p: FloatSequence
         if periodic:
             weights_p = np.tile(weights,27)                                                         # Laguerre weights (1,2,3,1,2,3,...,1,2,3)
             seeds_p = np.vstack((seeds  -np.array([size[0],0.,0.]),seeds,  seeds  +np.array([size[0],0.,0.])))
@@ -452,7 +453,7 @@ class Grid:
                                   size: FloatSequence,
                                   seeds: np.ndarray,
                                   material: IntSequence = None,
-                                  periodic: bool = True) -> "Grid":
+                                  periodic: bool = True) -> 'Grid':
         """
         Create grid from Voronoi tessellation.
 
@@ -538,7 +539,7 @@ class Grid:
                              surface: str,
                              threshold: float = 0.0,
                              periods: int = 1,
-                             materials: IntSequence = (0,1)) -> "Grid":
+                             materials: IntSequence = (0,1)) -> 'Grid':
         """
         Create grid from definition of triply periodic minimal surface.
 
@@ -684,7 +685,7 @@ class Grid:
                       fill: int = None,
                       R: Rotation = Rotation(),
                       inverse: bool = False,
-                      periodic: bool = True) -> "Grid":
+                      periodic: bool = True) -> 'Grid':
         """
         Insert a primitive geometric object at a given position.
 
@@ -769,7 +770,7 @@ class Grid:
                    )
 
 
-    def mirror(self, directions: Sequence[str], reflect: bool = False) -> "Grid":
+    def mirror(self, directions: Sequence[str], reflect: bool = False) -> 'Grid':
         """
         Mirror grid along given directions.
 
@@ -821,7 +822,7 @@ class Grid:
                    )
 
 
-    def flip(self, directions: Sequence[str]) -> "Grid":
+    def flip(self, directions: Union[Literal['x', 'y', 'z'], Sequence[Literal['x', 'y', 'z']]]) -> 'Grid':
         """
         Flip grid along given directions.
 
@@ -851,7 +852,7 @@ class Grid:
                    )
 
 
-    def scale(self, cells: IntSequence, periodic: bool = True) -> "Grid":
+    def scale(self, cells: IntSequence, periodic: bool = True) -> 'Grid':
         """
         Scale grid to new cells.
 
@@ -898,7 +899,7 @@ class Grid:
     def clean(self,
               stencil: int = 3,
               selection: IntSequence = None,
-              periodic: bool = True) -> "Grid":
+              periodic: bool = True) -> 'Grid':
         """
         Smooth grid by selecting most frequent material index within given stencil at each location.
 
@@ -938,7 +939,7 @@ class Grid:
                    )
 
 
-    def renumber(self) -> "Grid":
+    def renumber(self) -> 'Grid':
         """
         Renumber sorted material indices as 0,...,N-1.
 
@@ -957,7 +958,7 @@ class Grid:
                    )
 
 
-    def rotate(self, R: Rotation, fill: int = None) -> "Grid":
+    def rotate(self, R: Rotation, fill: int = None) -> 'Grid':
         """
         Rotate grid (pad if required).
 
@@ -997,7 +998,7 @@ class Grid:
     def canvas(self,
                cells: IntSequence = None,
                offset: IntSequence = None,
-               fill: int = None) -> "Grid":
+               fill: int = None) -> 'Grid':
         """
         Crop or enlarge/pad grid.
 
@@ -1048,7 +1049,7 @@ class Grid:
                    )
 
 
-    def substitute(self, from_material: IntSequence, to_material: IntSequence) -> "Grid":
+    def substitute(self, from_material: IntSequence, to_material: IntSequence) -> 'Grid':
         """
         Substitute material indices.
 
@@ -1076,7 +1077,7 @@ class Grid:
                    )
 
 
-    def sort(self) -> "Grid":
+    def sort(self) -> 'Grid':
         """
         Sort material indices such that min(material) is located at (0,0,0).
 
@@ -1102,7 +1103,7 @@ class Grid:
                         vicinity: int = 1,
                         offset: int = None,
                         trigger: IntSequence = [],
-                        periodic: bool = True) -> "Grid":
+                        periodic: bool = True) -> 'Grid':
         """
         Offset material index of points in the vicinity of xxx.
 
diff --git a/python/damask/_vtk.py b/python/damask/_vtk.py
index 6bb7a5d1c..4e3f27e0e 100644
--- a/python/damask/_vtk.py
+++ b/python/damask/_vtk.py
@@ -2,6 +2,7 @@ import os
 import warnings
 import multiprocessing as mp
 from pathlib import Path
+from typing import Union, Literal, List
 
 import numpy as np
 import vtk
@@ -9,6 +10,7 @@ from vtk.util.numpy_support import numpy_to_vtk            as np_to_vtk
 from vtk.util.numpy_support import numpy_to_vtkIdTypeArray as np_to_vtkIdTypeArray
 from vtk.util.numpy_support import vtk_to_numpy            as vtk_to_np
 
+from ._typehints import FloatSequence, IntSequence
 from . import util
 from . import Table
 
@@ -20,7 +22,7 @@ class VTK:
     High-level interface to VTK.
     """
 
-    def __init__(self,vtk_data):
+    def __init__(self, vtk_data: vtk.vtkDataSet):
         """
         New spatial visualization.
 
@@ -36,7 +38,7 @@ class VTK:
 
 
     @staticmethod
-    def from_image_data(cells,size,origin=np.zeros(3)):
+    def from_image_data(cells: IntSequence, size: FloatSequence, origin: FloatSequence = np.zeros(3)) -> 'VTK':
         """
         Create VTK of type vtk.vtkImageData.
 
@@ -60,13 +62,13 @@ class VTK:
         vtk_data = vtk.vtkImageData()
         vtk_data.SetDimensions(*(np.array(cells)+1))
         vtk_data.SetOrigin(*(np.array(origin)))
-        vtk_data.SetSpacing(*(size/cells))
+        vtk_data.SetSpacing(*(np.array(size)/np.array(cells)))
 
         return VTK(vtk_data)
 
 
     @staticmethod
-    def from_rectilinear_grid(grid,size,origin=np.zeros(3)):
+    def from_rectilinear_grid(grid: np.ndarray, size: FloatSequence, origin: FloatSequence = np.zeros(3)) -> 'VTK':
         """
         Create VTK of type vtk.vtkRectilinearGrid.
 
@@ -98,7 +100,7 @@ class VTK:
 
 
     @staticmethod
-    def from_unstructured_grid(nodes,connectivity,cell_type):
+    def from_unstructured_grid(nodes: np.ndarray, connectivity: np.ndarray, cell_type: str) -> 'VTK':
         """
         Create VTK of type vtk.vtkUnstructuredGrid.
 
@@ -138,7 +140,7 @@ class VTK:
 
 
     @staticmethod
-    def from_poly_data(points):
+    def from_poly_data(points: np.ndarray) -> 'VTK':
         """
         Create VTK of type vtk.polyData.
 
@@ -172,15 +174,17 @@ class VTK:
 
 
     @staticmethod
-    def load(fname,dataset_type=None):
+    def load(fname: Union[str, Path],
+             dataset_type: Literal['ImageData', 'UnstructuredGrid', 'PolyData'] = None) -> 'VTK':
         """
         Load from VTK file.
 
         Parameters
         ----------
         fname : str or pathlib.Path
-            Filename for reading. Valid extensions are .vti, .vtr, .vtu, .vtp, and .vtk.
-        dataset_type : {'vtkImageData', ''vtkRectilinearGrid', 'vtkUnstructuredGrid', 'vtkPolyData'}, optional
+            Filename for reading.
+            Valid extensions are .vti, .vtr, .vtu, .vtp, and .vtk.
+        dataset_type : {'ImageData', 'UnstructuredGrid', 'PolyData'}, optional
             Name of the vtk.vtkDataSet subclass when opening a .vtk file.
 
         Returns
@@ -234,7 +238,7 @@ class VTK:
     def _write(writer):
         """Wrapper for parallel writing."""
         writer.Write()
-    def save(self,fname,parallel=True,compress=True):
+    def save(self, fname: Union[str, Path], parallel: bool = True, compress: bool = True):
         """
         Save as VTK file.
 
@@ -280,7 +284,7 @@ class VTK:
 
     # Check https://blog.kitware.com/ghost-and-blanking-visibility-changes/ for missing data
     # Needs support for damask.Table
-    def add(self,data,label=None):
+    def add(self, data: Union[np.ndarray, np.ma.MaskedArray], label: str = None):
         """
         Add data to either cells or points.
 
@@ -327,7 +331,7 @@ class VTK:
             raise TypeError
 
 
-    def get(self,label):
+    def get(self, label: str) -> np.ndarray:
         """
         Get either cell or point data.
 
@@ -369,7 +373,7 @@ class VTK:
             raise ValueError(f'Array "{label}" not found.')
 
 
-    def get_comments(self):
+    def get_comments(self) -> List[str]:
         """Return the comments."""
         fielddata = self.vtk_data.GetFieldData()
         for a in range(fielddata.GetNumberOfArrays()):
@@ -379,7 +383,7 @@ class VTK:
         return []
 
 
-    def set_comments(self,comments):
+    def set_comments(self, comments: Union[str, List[str]]):
         """
         Set comments.
 
@@ -396,7 +400,7 @@ class VTK:
         self.vtk_data.GetFieldData().AddArray(s)
 
 
-    def add_comments(self,comments):
+    def add_comments(self, comments: Union[str, List[str]]):
         """
         Add comments.
 
@@ -409,7 +413,7 @@ class VTK:
         self.set_comments(self.get_comments() + ([comments] if isinstance(comments,str) else comments))
 
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         """ASCII representation of the VTK data."""
         writer = vtk.vtkDataSetWriter()
         writer.SetHeader(f'# {util.execution_stamp("VTK")}')
@@ -419,7 +423,7 @@ class VTK:
         return writer.GetOutputString()
 
 
-    def show(self) -> None:
+    def show(self):
         """
         Render.
 
diff --git a/python/damask/seeds.py b/python/damask/seeds.py
index 6ff150df3..e6d1f9613 100644
--- a/python/damask/seeds.py
+++ b/python/damask/seeds.py
@@ -79,7 +79,7 @@ def from_Poisson_disc(size: _FloatSequence, N_seeds: int, N_candidates: int, dis
 
     s = 1
     i = 0
-    progress = _util._ProgressBar(N_seeds+1,'',50)
+    progress = _util.ProgressBar(N_seeds+1,'',50)
     while s < N_seeds:
         i += 1
         candidates = rng.random((N_candidates,3))*_np.broadcast_to(size,(N_candidates,3))
diff --git a/python/damask/util.py b/python/damask/util.py
index 0581302db..2872762b9 100644
--- a/python/damask/util.py
+++ b/python/damask/util.py
@@ -7,12 +7,16 @@ import subprocess
 import shlex
 import re
 import fractions
+import collections.abc as abc
 from functools import reduce
+from typing import Union, Tuple, Iterable, Callable, Dict, List, Any, Literal, Optional
+from pathlib import Path
 
 import numpy as np
 import h5py
 
 from . import version
+from ._typehints import FloatSequence
 
 # limit visibility
 __all__=[
@@ -50,16 +54,16 @@ _colors = {
 ####################################################################################################
 # Functions
 ####################################################################################################
-def srepr(arg,glue = '\n'):
+def srepr(msg, glue: str = '\n') -> str:
     r"""
     Join items with glue string.
 
     Parameters
     ----------
-    arg : iterable
+    msg : object with __repr__ or sequence of objects with __repr__
         Items to join.
     glue : str, optional
-        Glue used for joining operation. Defaults to \n.
+        Glue used for joining operation. Defaults to '\n'.
 
     Returns
     -------
@@ -67,21 +71,21 @@ def srepr(arg,glue = '\n'):
         String representation of the joined items.
 
     """
-    if (not hasattr(arg, 'strip') and
-           (hasattr(arg, '__getitem__') or
-            hasattr(arg, '__iter__'))):
-        return glue.join(str(x) for x in arg)
+    if (not hasattr(msg, 'strip') and
+           (hasattr(msg, '__getitem__') or
+            hasattr(msg, '__iter__'))):
+        return glue.join(str(x) for x in msg)
     else:
-       return arg if isinstance(arg,str) else repr(arg)
+       return msg if isinstance(msg,str) else repr(msg)
 
 
-def emph(what):
+def emph(msg) -> str:
     """
     Format with emphasis.
 
     Parameters
     ----------
-    what : object with __repr__ or iterable of objects with __repr__.
+    msg : object with __repr__ or sequence of objects with __repr__
         Message to format.
 
     Returns
@@ -90,15 +94,15 @@ def emph(what):
         Formatted string representation of the joined items.
 
     """
-    return _colors['bold']+srepr(what)+_colors['end_color']
+    return _colors['bold']+srepr(msg)+_colors['end_color']
 
-def deemph(what):
+def deemph(msg) -> str:
     """
     Format with deemphasis.
 
     Parameters
     ----------
-    what : object with __repr__ or iterable of objects with __repr__.
+    msg : object with __repr__ or sequence of objects with __repr__
         Message to format.
 
     Returns
@@ -107,15 +111,15 @@ def deemph(what):
         Formatted string representation of the joined items.
 
     """
-    return _colors['dim']+srepr(what)+_colors['end_color']
+    return _colors['dim']+srepr(msg)+_colors['end_color']
 
-def warn(what):
+def warn(msg) -> str:
     """
     Format for warning.
 
     Parameters
     ----------
-    what : object with __repr__ or iterable of objects with __repr__.
+    msg : object with __repr__ or sequence of objects with __repr__
         Message to format.
 
     Returns
@@ -124,15 +128,15 @@ def warn(what):
         Formatted string representation of the joined items.
 
     """
-    return _colors['warning']+emph(what)+_colors['end_color']
+    return _colors['warning']+emph(msg)+_colors['end_color']
 
-def strikeout(what):
+def strikeout(msg) -> str:
     """
     Format as strikeout.
 
     Parameters
     ----------
-    what : object with __repr__ or iterable of objects with __repr__.
+    msg : object with __repr__ or iterable of objects with __repr__
         Message to format.
 
     Returns
@@ -141,10 +145,10 @@ def strikeout(what):
         Formatted string representation of the joined items.
 
     """
-    return _colors['crossout']+srepr(what)+_colors['end_color']
+    return _colors['crossout']+srepr(msg)+_colors['end_color']
 
 
-def run(cmd,wd='./',env=None,timeout=None):
+def run(cmd: str, wd: str = './', env: Dict[str, str] = None, timeout: int = None) -> Tuple[str, str]:
     """
     Run a command.
 
@@ -153,7 +157,7 @@ def run(cmd,wd='./',env=None,timeout=None):
     cmd : str
         Command to be executed.
     wd : str, optional
-        Working directory of process. Defaults to ./ .
+        Working directory of process. Defaults to './'.
     env : dict, optional
         Environment for execution.
     timeout : integer, optional
@@ -185,7 +189,7 @@ def run(cmd,wd='./',env=None,timeout=None):
 execute = run
 
 
-def natural_sort(key):
+def natural_sort(key: str) -> List[Union[int, str]]:
     """
     Natural sort.
 
@@ -200,7 +204,10 @@ def natural_sort(key):
     return [ convert(c) for c in re.split('([0-9]+)', key) ]
 
 
-def show_progress(iterable,N_iter=None,prefix='',bar_length=50):
+def show_progress(iterable: Iterable,
+                  N_iter: int = None,
+                  prefix: str = '',
+                  bar_length: int = 50) -> Any:
     """
     Decorate a loop with a progress bar.
 
@@ -208,39 +215,49 @@ def show_progress(iterable,N_iter=None,prefix='',bar_length=50):
 
     Parameters
     ----------
-    iterable : iterable or function with yield statement
-        Iterable (or function with yield statement) to be decorated.
+    iterable : iterable
+        Iterable to be decorated.
     N_iter : int, optional
-        Total number of iterations. Required unless obtainable as len(iterable).
+        Total number of iterations. Required if iterable is not a sequence.
     prefix : str, optional
         Prefix string.
     bar_length : int, optional
         Length of progress bar in characters. Defaults to 50.
 
     """
-    if N_iter in [0,1] or (hasattr(iterable,'__len__') and len(iterable) <= 1):
+    if isinstance(iterable,abc.Sequence):
+       if N_iter is None:
+          N = len(iterable)
+       else:
+          raise ValueError('N_iter given for sequence')
+    else:
+       if N_iter is None:
+          raise ValueError('N_iter not given')
+       else:
+          N = N_iter
+
+    if N <= 1:
         for item in iterable:
             yield item
     else:
-        status = _ProgressBar(N_iter if N_iter is not None else len(iterable),prefix,bar_length)
-
+        status = ProgressBar(N,prefix,bar_length)
         for i,item in enumerate(iterable):
             yield item
             status.update(i)
 
 
-def scale_to_coprime(v):
+def scale_to_coprime(v: FloatSequence) -> np.ndarray:
     """
     Scale vector to co-prime (relatively prime) integers.
 
     Parameters
     ----------
-    v : numpy.ndarray of shape (:)
+    v : sequence of float, len (:)
         Vector to scale.
 
     Returns
     -------
-    m : numpy.ndarray of shape (:)
+    m : numpy.ndarray, shape (:)
         Vector scaled to co-prime numbers.
 
     """
@@ -257,17 +274,21 @@ def scale_to_coprime(v):
         except AttributeError:
             return a * b // np.gcd(a, b)
 
-    m = (np.array(v) * reduce(lcm, map(lambda x: int(get_square_denominator(x)),v)) ** 0.5).astype(int)
+    v_ = np.array(v)
+    m = (v_ * reduce(lcm, map(lambda x: int(get_square_denominator(x)),v_))**0.5).astype(int)
     m = m//reduce(np.gcd,m)
 
     with np.errstate(invalid='ignore'):
-        if not np.allclose(np.ma.masked_invalid(v/m),v[np.argmax(abs(v))]/m[np.argmax(abs(v))]):
-            raise ValueError(f'Invalid result {m} for input {v}. Insufficient precision?')
+        if not np.allclose(np.ma.masked_invalid(v_/m),v_[np.argmax(abs(v_))]/m[np.argmax(abs(v_))]):
+            raise ValueError(f'Invalid result {m} for input {v_}. Insufficient precision?')
 
     return m
 
 
-def project_equal_angle(vector,direction='z',normalize=True,keepdims=False):
+def project_equal_angle(vector: np.ndarray,
+                        direction: Literal['x', 'y', 'z'] = 'z',
+                        normalize: bool = True,
+                        keepdims: bool = False) -> np.ndarray:
     """
     Apply equal-angle projection to vector.
 
@@ -275,9 +296,8 @@ def project_equal_angle(vector,direction='z',normalize=True,keepdims=False):
     ----------
     vector : numpy.ndarray, shape (...,3)
         Vector coordinates to be projected.
-    direction : str
-        Projection direction 'x', 'y', or 'z'.
-        Defaults to 'z'.
+    direction : {'x', 'y', 'z'}
+        Projection direction. Defaults to 'z'.
     normalize : bool
         Ensure unit length of input vector. Defaults to True.
     keepdims : bool
@@ -309,7 +329,10 @@ def project_equal_angle(vector,direction='z',normalize=True,keepdims=False):
     return np.roll(np.block([v[...,:2]/(1.0+np.abs(v[...,2:3])),np.zeros_like(v[...,2:3])]),
                    -shift if keepdims else 0,axis=-1)[...,:3 if keepdims else 2]
 
-def project_equal_area(vector,direction='z',normalize=True,keepdims=False):
+def project_equal_area(vector: np.ndarray,
+                       direction: Literal['x', 'y', 'z'] = 'z',
+                       normalize: bool = True,
+                       keepdims: bool = False) -> np.ndarray:
     """
     Apply equal-area projection to vector.
 
@@ -317,9 +340,8 @@ def project_equal_area(vector,direction='z',normalize=True,keepdims=False):
     ----------
     vector : numpy.ndarray, shape (...,3)
         Vector coordinates to be projected.
-    direction : str
-        Projection direction 'x', 'y', or 'z'.
-        Defaults to 'z'.
+    direction : {'x', 'y', 'z'}
+        Projection direction. Defaults to 'z'.
     normalize : bool
         Ensure unit length of input vector. Defaults to True.
     keepdims : bool
@@ -351,15 +373,14 @@ def project_equal_area(vector,direction='z',normalize=True,keepdims=False):
     return np.roll(np.block([v[...,:2]/np.sqrt(1.0+np.abs(v[...,2:3])),np.zeros_like(v[...,2:3])]),
                    -shift if keepdims else 0,axis=-1)[...,:3 if keepdims else 2]
 
-
-def execution_stamp(class_name,function_name=None):
+def execution_stamp(class_name: str, function_name: str = None) -> str:
     """Timestamp the execution of a (function within a) class."""
     now = datetime.datetime.now().astimezone().strftime('%Y-%m-%d %H:%M:%S%z')
     _function_name = '' if function_name is None else f'.{function_name}'
     return f'damask.{class_name}{_function_name} v{version} ({now})'
 
 
-def hybrid_IA(dist,N,rng_seed=None):
+def hybrid_IA(dist: np.ndarray, N: int, rng_seed = None) -> np.ndarray:
     """
     Hybrid integer approximation.
 
@@ -387,7 +408,10 @@ def hybrid_IA(dist,N,rng_seed=None):
     return np.repeat(np.arange(len(dist)),repeats)[np.random.default_rng(rng_seed).permutation(N_inv_samples)[:N]]
 
 
-def shapeshifter(fro,to,mode='left',keep_ones=False):
+def shapeshifter(fro: Tuple[int, ...],
+                 to: Tuple[int, ...],
+                 mode: Literal['left','right'] = 'left',
+                 keep_ones: bool = False) -> Tuple[Optional[int], ...]:
     """
     Return dimensions that reshape 'fro' to become broadcastable to 'to'.
 
@@ -398,9 +422,9 @@ def shapeshifter(fro,to,mode='left',keep_ones=False):
     to : tuple
         Target shape of array after broadcasting.
         len(to) cannot be less than len(fro).
-    mode : str, optional
+    mode : {'left', 'right'}, optional
         Indicates whether new axes are preferably added to
-        either 'left' or 'right' of the original shape.
+        either left or right of the original shape.
         Defaults to 'left'.
     keep_ones : bool, optional
         Treat '1' in fro as literal value instead of dimensional placeholder.
@@ -434,21 +458,22 @@ def shapeshifter(fro,to,mode='left',keep_ones=False):
     fro = (1,) if not len(fro) else fro
     to  = (1,) if not len(to)  else to
     try:
-        grp = re.match(beg[mode]
+        match = re.match(beg[mode]
                       +f',{sep[mode]}'.join(map(lambda x: f'{x}'
                                                           if x>1 or (keep_ones and len(fro)>1) else
                                                           '\\d+',fro))
-                      +f',{end[mode]}',
-                       ','.join(map(str,to))+',').groups()
-    except AttributeError:
+                      +f',{end[mode]}',','.join(map(str,to))+',')
+        assert match
+        grp = match.groups()
+    except AssertionError:
         raise ValueError(f'Shapes can not be shifted {fro} --> {to}')
-    fill = ()
+    fill: Tuple[Optional[int], ...] = ()
     for g,d in zip(grp,fro+(None,)):
         fill += (1,)*g.count(',')+(d,)
     return fill[:-1]
 
 
-def shapeblender(a,b):
+def shapeblender(a: Tuple[int, ...], b: Tuple[int, ...]) -> Tuple[int, ...]:
     """
     Return a shape that overlaps the rightmost entries of 'a' with the leftmost of 'b'.
 
@@ -476,7 +501,7 @@ def shapeblender(a,b):
     return a + b[i:]
 
 
-def extend_docstring(extra_docstring):
+def extend_docstring(extra_docstring: str) -> Callable:
     """
     Decorator: Append to function's docstring.
 
@@ -492,7 +517,7 @@ def extend_docstring(extra_docstring):
     return _decorator
 
 
-def extended_docstring(f,extra_docstring):
+def extended_docstring(f: Callable, extra_docstring: str) -> Callable:
     """
     Decorator: Combine another function's docstring with a given docstring.
 
@@ -510,7 +535,7 @@ def extended_docstring(f,extra_docstring):
     return _decorator
 
 
-def DREAM3D_base_group(fname):
+def DREAM3D_base_group(fname: Union[str, Path]) -> str:
     """
     Determine the base group of a DREAM.3D file.
 
@@ -536,7 +561,7 @@ def DREAM3D_base_group(fname):
 
     return base_group
 
-def DREAM3D_cell_data_group(fname):
+def DREAM3D_cell_data_group(fname: Union[str, Path]) -> str:
     """
     Determine the cell data group of a DREAM.3D file.
 
@@ -568,18 +593,18 @@ def DREAM3D_cell_data_group(fname):
     return cell_data_group
 
 
-def Bravais_to_Miller(*,uvtw=None,hkil=None):
+def Bravais_to_Miller(*, uvtw: np.ndarray = None, hkil: np.ndarray = None) -> np.ndarray:
     """
     Transform 4 Miller–Bravais indices to 3 Miller indices of crystal direction [uvw] or plane normal (hkl).
 
     Parameters
     ----------
-    uvtw|hkil : numpy.ndarray of shape (...,4)
+    uvtw|hkil : numpy.ndarray, shape (...,4)
         Miller–Bravais indices of crystallographic direction [uvtw] or plane normal (hkil).
 
     Returns
     -------
-    uvw|hkl : numpy.ndarray of shape (...,3)
+    uvw|hkl : numpy.ndarray, shape (...,3)
         Miller indices of [uvw] direction or (hkl) plane normal.
 
     """
@@ -595,18 +620,18 @@ def Bravais_to_Miller(*,uvtw=None,hkil=None):
     return np.einsum('il,...l',basis,axis)
 
 
-def Miller_to_Bravais(*,uvw=None,hkl=None):
+def Miller_to_Bravais(*, uvw: np.ndarray = None, hkl: np.ndarray = None) -> np.ndarray:
     """
     Transform 3 Miller indices to 4 Miller–Bravais indices of crystal direction [uvtw] or plane normal (hkil).
 
     Parameters
     ----------
-    uvw|hkl : numpy.ndarray of shape (...,3)
+    uvw|hkl : numpy.ndarray, shape (...,3)
         Miller indices of crystallographic direction [uvw] or plane normal (hkl).
 
     Returns
     -------
-    uvtw|hkil : numpy.ndarray of shape (...,4)
+    uvtw|hkil : numpy.ndarray, shape (...,4)
         Miller–Bravais indices of [uvtw] direction or (hkil) plane normal.
 
     """
@@ -624,7 +649,7 @@ def Miller_to_Bravais(*,uvw=None,hkl=None):
     return np.einsum('il,...l',basis,axis)
 
 
-def dict_prune(d):
+def dict_prune(d: Dict) -> Dict:
     """
     Recursively remove empty dictionaries.
 
@@ -650,7 +675,7 @@ def dict_prune(d):
     return new
 
 
-def dict_flatten(d):
+def dict_flatten(d: Dict) -> Dict:
     """
     Recursively remove keys of single-entry dictionaries.
 
@@ -678,14 +703,14 @@ def dict_flatten(d):
 ####################################################################################################
 # Classes
 ####################################################################################################
-class _ProgressBar:
+class ProgressBar:
     """
     Report progress of an interation as a status bar.
 
     Works for 0-based loops, ETA is estimated by linear extrapolation.
     """
 
-    def __init__(self,total,prefix,bar_length):
+    def __init__(self, total: int, prefix: str, bar_length: int):
         """
         Set current time as basis for ETA estimation.
 
@@ -708,7 +733,7 @@ class _ProgressBar:
         sys.stderr.write(f"{self.prefix} {'░'*self.bar_length}   0% ETA n/a")
         sys.stderr.flush()
 
-    def update(self,iteration):
+    def update(self, iteration: int) -> None:
 
         fraction = (iteration+1) / self.total
         filled_length = int(self.bar_length * fraction)