Address fact that typing.Deque wasn't defined prior to 3.5.4

Author: tleonhardt

cmd2/table_creator.py

@@ -10,12 +10,20 @@
 import io
 from collections import deque
 from enum import Enum
-from typing import Any, Deque, Optional, Sequence, Tuple, Union
+from typing import Any, Optional, Sequence, Tuple, Union
 
 from wcwidth import wcwidth
 
 from . import ansi, constants, utils
 
+# This is needed for compatibility with early versions of Python 3.5 prior to 3.5.4
+try:
+    from typing import Deque
+except ImportError:
+    from typing import _alias, T
+    import collections
+    Deque = _alias(collections.deque, T)
+
 # Constants
 EMPTY = ''
 SPACE = ' '

docs/conf.py

@@ -19,6 +19,7 @@
 """
 # Import for custom theme from Read the Docs
 import sphinx_rtd_theme
+
 import cmd2
 
 # -- General configuration -----------------------------------------------------