Merge pull request #762 from jathpala/collections.abc

Corrects import of MutableMapping class for python 3.3+ (required for 3.8)

Author: effigies

nibabel/streamlines/tractogram.py

@@ -1,9 +1,14 @@
 import copy
 import numbers
 import numpy as np
-import collections
 from warnings import warn
 
+try:
+    from collections.abc import MutableMapping
+except ImportError:
+    # PY2 compatibility
+    from collections import MutableMapping
+
 from nibabel.affines import apply_affine
 
 from .array_sequence import ArraySequence
@@ -19,7 +24,7 @@ def is_lazy_dict(obj):
     return is_data_dict(obj) and callable(list(obj.store.values())[0])
 
 
-class SliceableDataDict(collections.MutableMapping):
+class SliceableDataDict(MutableMapping):
     """ Dictionary for which key access can do slicing on the values.
 
     This container behaves like a standard dictionary but extends key access to
@@ -181,7 +186,7 @@ def _extend_entry(self, key, value):
         self[key].extend(value)
 
 
-class LazyDict(collections.MutableMapping):
+class LazyDict(MutableMapping):
     """ Dictionary of generator functions.
 
     This container behaves like a dictionary but it makes sure its elements are