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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 all_reference_commits(self):
 """ Returns the current DataFrame joined with the commits DataFrame, with all of the commits in all references. Take into account that getting all the commits will lead to a lot of repeated tree entries and blobs, thus making your query very slow. Most of the time, you just want the HEAD commit of each reference: :rtype: CommitsDataFrame """

        return CommitsDataFrame(self._engine_dataframe.getAllReferenceCommits(), self._session, self._implicits)