diff -r 1ce7a55b09d1 -r b1fb341d8a61 contrib/python-zstandard/zstandard/__init__.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/contrib/python-zstandard/zstandard/__init__.py	Mon Apr 09 10:13:29 2018 -0700
@@ -0,0 +1,62 @@
+# Copyright (c) 2017-present, Gregory Szorc
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license. See the LICENSE file for details.
+
+"""Python interface to the Zstandard (zstd) compression library."""
+
+from __future__ import absolute_import, unicode_literals
+
+# This module serves 2 roles:
+#
+# 1) Export the C or CFFI "backend" through a central module.
+# 2) Implement additional functionality built on top of C or CFFI backend.
+
+import os
+import platform
+
+# Some Python implementations don't support C extensions. That's why we have
+# a CFFI implementation in the first place. The code here import one of our
+# "backends" then re-exports the symbols from this module. For convenience,
+# we support falling back to the CFFI backend if the C extension can't be
+# imported. But for performance reasons, we only do this on unknown Python
+# implementation. Notably, for CPython we require the C extension by default.
+# Because someone will inevitably want special behavior, the behavior is
+# configurable via an environment variable. A potentially better way to handle
+# this is to import a special ``__importpolicy__`` module or something
+# defining a variable and `setup.py` could write the file with whatever
+# policy was specified at build time. Until someone needs it, we go with
+# the hacky but simple environment variable approach.
+_module_policy = os.environ.get('PYTHON_ZSTANDARD_IMPORT_POLICY', 'default')
+
+if _module_policy == 'default':
+    if platform.python_implementation() in ('CPython',):
+        from zstd import *
+        backend = 'cext'
+    elif platform.python_implementation() in ('PyPy',):
+        from zstd_cffi import *
+        backend = 'cffi'
+    else:
+        try:
+            from zstd import *
+            backend = 'cext'
+        except ImportError:
+            from zstd_cffi import *
+            backend = 'cffi'
+elif _module_policy == 'cffi_fallback':
+    try:
+        from zstd import *
+        backend = 'cext'
+    except ImportError:
+        from zstd_cffi import *
+        backend = 'cffi'
+elif _module_policy == 'cext':
+    from zstd import *
+    backend = 'cext'
+elif _module_policy == 'cffi':
+    from zstd_cffi import *
+    backend = 'cffi'
+else:
+    raise ImportError('unknown module import policy: %s; use default, cffi_fallback, '
+                      'cext, or cffi' % _module_policy)