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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 callable(self) -> Optional[str]: """Show the name of the current callable in the trace"""

        if self.current_trace_frame_index != -1:
            return self._get_callable_from_trace_tuple(
                self.trace_tuples[self.current_trace_frame_index]
            )[0]
        return None