Allow reimport of a module within a function
Reject incompatible imports with the same name
Add missing typing imports to test cases
Fix comment in test typing stub
Support full stub tests that fail type checking
Don't propagate names imported in builtins

This fixes the problem of names in typing such as 'Any' being visible
everywhere implicitly.
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Work around emacs auto-indent problem
Semantically analyze typevar values
Propagate typevar values to TypeDefs
Check type arg values in type semantic analysis

Check that type variable value restrictions are honored.
Fix references to Iterator/Iterable

Types defined in typing are no longer available via builtins.
Check typevar values in type application
Add values attribute to TypeVar
Fixes to checking typevar value restrictions
Add typevar value restriction test case
Check generic class body with typevar values

The implementation is incomplete.
Fix missing imports from typing
Fix broken type annotation