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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 get_changeset(self, revision=None):
 """ Returns ``MercurialChangeset`` object representing repository's changeset at the given ``revision``. """

        revision = self._get_revision(revision)
        changeset = MercurialChangeset(repository=self, revision=revision)
        return changeset