code: def visit_FunctionDef(self, node):
          
          self.symbols.pop(node.name, None)
          gsymbols = self.symbols.copy()
          [self.symbols.pop(arg.id, None) for arg in node.args.args]
          self.generic_visit(node)
          self.symbols = gsymbols
          return node
docs: Update import context using overwriting name information.
  
          Examples
          --------
          >> import foo
          >> import bar
          >> def foo(bar):
          >>     print(bar)
  
          In this case, neither bar nor foo can be used in the foo function and
          in future function, foo will not be usable.