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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 context_id(self):
 """Return this Async's Context Id if it exists."""

        if not self._context_id:
            self._context_id = self._get_context_id()
            self.update_options(context_id=self._context_id)

        return self._context_id