Add __future__.py to std library, + dull test to verify that assignments

therein are of the proper form.

1 files changed, 44 insertions, 0 deletions

diff --git a/Lib/__future__.py b/Lib/__future__.py
new file mode 100644
index 0000000..c50b810
--- /dev/null
+++ b/Lib/__future__.py
@@ -0,0 +1,44 @@
+"""__future__:  Record of phased-in incompatible language changes.
+
+Each line is of the form:
+
+    FeatureName = ReleaseInfo
+
+ReleaseInfo is a pair of the form:
+
+    (OptionalRelease, MandatoryRelease)
+
+where, normally, OptionalRelease < MandatoryRelease, and both are 5-tuples
+of the same form as sys.version_info:
+
+    (PY_MAJOR_VERSION, # the 2 in 2.1.0a3; an int
+     PY_MINOR_VERSION, # the 1; an int
+     PY_MICRO_VERSION, # the 0; an int
+     PY_RELEASE_LEVEL, # "alpha", "beta", "candidate" or "final"; string
+     PY_RELEASE_SERIAL # the 3; an int
+    )
+
+OptionalRelease records the first release in which
+
+    from __future__ import FeatureName
+
+was accepted.
+
+In the case of MandatoryReleases that have not yet occurred, 
+MandatoryRelease predicts the release in which the feature will become part 
+of the language.
+
+Else MandatoryRelease records when the feature became part of the language; 
+in releases at or after that, modules no longer need
+
+    from __future__ import FeatureName
+
+to use the feature in question, but may continue to use such imports.
+
+MandatoryRelease may also be None, meaning that a planned feature got 
+dropped.
+
+No line is ever to be deleted from this file.
+"""
+
+nested_scopes = (2, 1, 0, "beta", 1), (2, 2, 0, "final", 0)