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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 _present_perm_set_for_subj(self, perm_dict, subj_str):
 """Return a set containing only the permissions that are present in the ``perm_dict`` for ``subj_str``"""

        return {p for p, s in list(perm_dict.items()) if subj_str in s}