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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 create_mod_site(self, mc):
 """Create modification site for the BaseAgent from a ModCondition."""

        site_name = get_mod_site_name(mc)
        (unmod_site_state, mod_site_state) = states[mc.mod_type]
        self.create_site(site_name, (unmod_site_state, mod_site_state))
        site_anns = [Annotation((site_name, mod_site_state), mc.mod_type,
                                'is_modification')]
        if mc.residue:
            site_anns.append(Annotation(site_name, mc.residue, 'is_residue'))
        if mc.position:
            site_anns.append(Annotation(site_name, mc.position, 'is_position'))
        self.site_annotations += site_anns