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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_modifications(self):
 """Extract INDRA Modification Statements from the BioPAX model. To extract Modifications, this method reuses the structure of BioPAX Pattern's org.biopax.paxtools.pattern.PatternBox.constrolsStateChange pattern with additional constraints to specify the type of state change occurring (phosphorylation, deubiquitination, etc.). """

        for modtype, modclass in modtype_to_modclass.items():
            # TODO: we could possibly try to also extract generic
            # modifications here
            if modtype == 'modification':
                continue
            stmts = self._get_generic_modification(modclass)
            self.statements += stmts