fix DeprecationWarning when importing ABCs

Author: mkcor

dash/development/base_component.py

@@ -1,7 +1,10 @@
-import collections
 import abc
 import inspect
 import sys
+try:
+    from collections.abc import MutableSequence
+except ImportError:
+    from collections import MutableSequence
 
 import six
 
@@ -53,8 +56,7 @@ def is_number(s):
 def _check_if_has_indexable_children(item):
     if (not hasattr(item, 'children') or
             (not isinstance(item.children, Component) and
-             not isinstance(item.children, (tuple,
-                                            collections.MutableSequence)))):
+             not isinstance(item.children, (tuple, MutableSequence)))):
 
         raise KeyError
 
@@ -153,7 +155,7 @@ def _get_set_or_delete(self, id, operation, new_item=None):
                 pass
 
         # if children is like a list
-        if isinstance(self.children, (tuple, collections.MutableSequence)):
+        if isinstance(self.children, (tuple, MutableSequence)):
             for i, item in enumerate(self.children):
                 # If the item itself is the one we're looking for
                 if getattr(item, 'id', None) == id:
@@ -229,7 +231,7 @@ def traverse_with_paths(self):
                 yield "\n".join(["[*] " + children_string, p]), t
 
         # children is a list of components
-        elif isinstance(children, (tuple, collections.MutableSequence)):
+        elif isinstance(children, (tuple, MutableSequence)):
             for idx, i in enumerate(children):
                 list_path = "[{:d}] {:s} {}".format(
                     idx,
@@ -262,7 +264,7 @@ def __len__(self):
         elif isinstance(self.children, Component):
             length = 1
             length += len(self.children)
-        elif isinstance(self.children, (tuple, collections.MutableSequence)):
+        elif isinstance(self.children, (tuple, MutableSequence)):
             for c in self.children:
                 length += 1
                 if isinstance(c, Component):