Add typing.py back (#58)

mode/utils/typing.py

@@ -0,0 +1,75 @@
+"""Backport of :mod:`typing` additions in Python 3.7."""
+
+# pragma: no cover
+import typing
+
+__all__ = [
+    "AsyncContextManager",
+    "AsyncGenerator",
+    "ChainMap",
+    "Counter",
+    "Deque",
+    "NoReturn",
+    "Protocol",
+]
+
+if typing.TYPE_CHECKING:
+    from typing import AsyncContextManager
+else:
+    try:
+        from typing import AsyncContextManager
+    except ImportError:
+        from typing import AsyncContextManager
+
+if typing.TYPE_CHECKING:
+    from typing import AsyncGenerator
+else:
+    try:
+        from typing import AsyncGenerator
+    except ImportError:  # Python 3.6.0
+        from typing import AsyncGenerator
+
+
+if typing.TYPE_CHECKING:
+    from typing import ChainMap
+else:
+    try:
+        from typing import ChainMap
+    except ImportError:
+        from typing import ChainMap
+
+
+if typing.TYPE_CHECKING:
+    from typing import Counter
+else:
+    try:
+        from typing import Counter
+    except ImportError:
+        from typing import Counter
+
+
+if typing.TYPE_CHECKING:
+    from typing import Deque
+else:
+    try:
+        from typing import Deque
+    except ImportError:
+        from typing import Deque
+
+
+if typing.TYPE_CHECKING:
+    from typing import NoReturn
+else:
+    try:
+        from typing import NoReturn
+    except ImportError:
+        from typing import NoReturn
+
+
+if typing.TYPE_CHECKING:
+    from typing import Protocol
+else:
+    try:
+        from typing import Protocol
+    except ImportError:
+        from typing_extensions import Protocol