parameters: (self, name)
return_statement: return name in self._functions
docstring: Tests whether 'name' is registered in this graph's function library.
  
      Args:
        name: string op name.
      Returns:
        bool indicating whether or not 'name' is registered in function library.
docstring_summary: Tests whether 'name' is registered in this graph's function library.
docstring_tokens: Tests whether name is registered in this graph s function library .
function: def _is_function(self, name):
      """Tests whether 'name' is registered in this graph's function library.
  
      Args:
        name: string op name.
      Returns:
        bool indicating whether or not 'name' is registered in function library.
      """
      return name in self._functions
function_tokens: def _is_function ( self , name ) : return name in self . _functions