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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 _track_tendril(self, tendril):
 """ Adds the tendril to the set of tracked tendrils. """


        self.tendrils[tendril._tendril_key] = tendril

        # Also add to _tendrils
        self._tendrils.setdefault(tendril.proto, weakref.WeakValueDictionary())
        self._tendrils[tendril.proto][tendril._tendril_key] = tendril