diff -r a2bf6d1e018e Doc/library/contextlib.rst
--- a/Doc/library/contextlib.rst	Fri Mar 18 13:24:15 2016 -0700
+++ b/Doc/library/contextlib.rst	Fri Mar 18 15:48:04 2016 -0700
@@ -18,6 +18,26 @@
 
 Functions and classes provided:
 
+.. class:: AbstractContextManager
+
+   An abstract base class for context managers. To learn the purposes of the
+   abstract methods of this class, see :ref:`typecontextmanager`.
+
+   .. abstractmethod:: __enter__(self)
+
+      Returns ``self``.
+
+   .. abstractmethod:: __exit__(self, exc_type, exc_value, traceback)
+
+      Returns ``None``.
+
+
+.. class:: ContextManagerType(typing.Generic[T])
+
+   A type representing context managers. The type that the :meth:`__enter__`
+   method returns can be specified, e.g. ``ContextManagerType[TextIO]``.
+
+
 .. decorator:: contextmanager
 
    This function is a :term:`decorator` that can be used to define a factory
diff -r a2bf6d1e018e Lib/contextlib.py
--- a/Lib/contextlib.py	Fri Mar 18 13:24:15 2016 -0700
+++ b/Lib/contextlib.py	Fri Mar 18 15:48:04 2016 -0700
@@ -1,6 +1,8 @@
 """Utilities for with-statement contexts.  See PEP 343."""
 
+import abc
 import sys
+import typing as t
 from collections import deque
 from functools import wraps
 
@@ -8,6 +10,28 @@
            "redirect_stdout", "redirect_stderr", "suppress"]
 
 
+class AbstractContextManager(abc.ABC):
+
+    """An abstract base class for context managers."""
+
+    @abc.abstractmethod
+    def __enter__(self):
+        """Return `self` upon entering the runtime context."""
+        return self
+
+    @abc.abstractmethod
+    def __exit__(self, exc_type, exc_value, traceback):
+        """Raise any exception triggered within the runtime context."""
+        return None
+
+
+class ContextManagerType(t.Generic[t.T], extra=AbstractContextManager):
+
+    """Context manager type."""
+
+    __slots__ = ()
+
+
 class ContextDecorator(object):
     "A base class or mixin that enables context managers to work as decorators."
 
@@ -31,7 +55,7 @@
         return inner
 
 
-class _GeneratorContextManager(ContextDecorator):
+class _GeneratorContextManager(ContextDecorator, AbstractContextManager):
     """Helper for @contextmanager decorator."""
 
     def __init__(self, func, args, kwds):
@@ -134,7 +158,7 @@
     return helper
 
 
-class closing(object):
+class closing(AbstractContextManager):
     """Context to automatically close something at the end of a block.
 
     Code like this:
@@ -159,7 +183,7 @@
         self.thing.close()
 
 
-class _RedirectStream:
+class _RedirectStream(AbstractContextManager):
 
     _stream = None
 
@@ -199,7 +223,7 @@
     _stream = "stderr"
 
 
-class suppress:
+class suppress(AbstractContextManager):
     """Context manager to suppress specified exceptions
 
     After the exception is suppressed, execution proceeds with the next
@@ -230,7 +254,7 @@
 
 
 # Inspired by discussions on http://bugs.python.org/issue13585
-class ExitStack(object):
+class ExitStack(AbstractContextManager):
     """Context manager for dynamic management of a stack of exit callbacks
 
     For example: