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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 trace_api(self):
 """ Helper for trace-related API calls. See https://cloud.google.com/trace/docs/reference/v2/rpc/google.devtools. cloudtrace.v2 """

        if self._trace_api is None:
            self._trace_api = make_trace_api(self)
        return self._trace_api