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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 reference(self, referencing_path=None):
 """How to reference this address in a BUILD file. :API: public """

    if referencing_path is not None and self._spec_path == referencing_path:
      return self.relative_spec
    elif os.path.basename(self._spec_path) != self._target_name:
      return self.spec
    else:
      return self._spec_path