set defaults for Literal[False], Literal[True], and None
          #1455
        
          
      
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assert_type()to assert the type of any return valueApplying #1453 (comment) to the whole codebase, for now just for the "simple and obvious" ones:
: Literal[True] = ...->: Literal[True] = True: Literal[False] = ...->: Literal[False] = False: None = ...->: None = None