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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 add_nexusport_binding(port_id, vlan_id, vni, switch_ip, instance_id, is_native=False, ch_grp=0):
 """Adds a nexusport binding."""

    LOG.debug("add_nexusport_binding() called")
    session = bc.get_writer_session()
    binding = nexus_models_v2.NexusPortBinding(port_id=port_id,
                  vlan_id=vlan_id,
                  vni=vni,
                  switch_ip=switch_ip,
                  instance_id=instance_id,
                  is_native=is_native,
                  channel_group=ch_grp)
    session.add(binding)
    session.flush()
    return binding