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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 remove_nexusport_binding(port_id, vlan_id, vni, switch_ip, instance_id):
 """Removes a nexusport binding."""

    LOG.debug("remove_nexusport_binding() called")
    session = bc.get_writer_session()
    binding = _lookup_all_nexus_bindings(session=session,
                                         vlan_id=vlan_id,
                                         vni=vni,
                                         switch_ip=switch_ip,
                                         port_id=port_id,
                                         instance_id=instance_id)
    for bind in binding:
        session.delete(bind)
    session.flush()
    return binding