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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_gap(self):
 """Extract Gap INDRA Statements from the BioPAX model. This method uses a custom BioPAX Pattern (one that is not implemented PatternBox) to query for controlled BiochemicalReactions in which the same protein is in complex with GTP on the left hand side and in complex with GDP on the right hand side. This implies that the controller is a GAP for the GDP/GTP-bound protein. """

        p = self._gef_gap_base()
        s = _bpp('Searcher')
        res = s.searchPlain(self.model, p)
        res_array = [_match_to_array(m) for m in res.toArray()]
        for r in res_array:
            controller_pe = r[p.indexOf('controller PE')]
            input_pe = r[p.indexOf('input PE')]
            input_spe = r[p.indexOf('input simple PE')]
            output_pe = r[p.indexOf('output PE')]
            output_spe = r[p.indexOf('output simple PE')]
            reaction = r[p.indexOf('Conversion')]
            control = r[p.indexOf('Control')]

            # Make sure the GAP is not a complex
            # TODO: it could be possible to extract certain complexes here, for
            # instance ones that only have a single protein
            if _is_complex(controller_pe):
                continue

            members_in = self._get_complex_members(input_pe)
            members_out = self._get_complex_members(output_pe)
            if not (members_in and members_out):
                continue
            # Make sure the outgoing complex has exactly 2 members
            # TODO: by finding matching proteins on either side, in principle
            # it would be possible to find Gap relationships in complexes
            # with more members
            if len(members_out) != 2:
                continue
            # Make sure complex starts with GDP that becomes GTP
            gtp_in = False
            for member in members_in:
                if isinstance(member, Agent) and member.name == 'GTP':
                    gtp_in = True
            gdp_out = False
            for member in members_out:
                if isinstance(member, Agent) and member.name == 'GDP':
                    gdp_out = True
            if not (gtp_in and gdp_out):
                continue
            ras_list = self._get_agents_from_entity(input_spe)
            gap_list = self._get_agents_from_entity(controller_pe)
            ev = self._get_evidence(control)
            for gap, ras in itertools.product(_listify(gap_list),
                                               _listify(ras_list)):
                st = Gap(gap, ras, evidence=ev)
                st_dec = decode_obj(st, encoding='utf-8')
                self.statements.append(st_dec)