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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def output_names(self):
 """A list of names for the outputs of this module."""

        if self.binded:
            return self._curr_module.output_names
        else:
            symbol, _, _ = self._call_sym_gen(self._default_bucket_key)
            return symbol.list_outputs()