Returns either (caller, caller_port) or (callee, callee_port).

def _get_callable_from_trace_tuple(
        self, trace_tuple: TraceTuple
    ) -> Tuple[str, str]:
        """Returns either (caller, caller_port) or (callee, callee_port).
        """
        trace_frame = trace_tuple.trace_frame
        if trace_tuple.placeholder:
            return trace_frame.caller, trace_frame.caller_port
        return trace_frame.callee, trace_frame.callee_port