code: def add_host_mapping(host_id, nexus_ip, interface, ch_grp, is_static):
      
  
      LOG.debug("add_nexusport_binding() called")
      session = bc.get_writer_session()
      mapping = nexus_models_v2.NexusHostMapping(host_id=host_id,
                    if_id=interface,
                    switch_ip=nexus_ip,
                    ch_grp=ch_grp,
                    is_static=is_static)
      try:
          session.add(mapping)
          session.flush()
      except db_exc.DBDuplicateEntry:
          with excutils.save_and_reraise_exception() as ctxt:
              if is_static:
                  ctxt.reraise = False
                  LOG.debug("Duplicate static entry encountered "
                            "host=%(host)s, if=%(if)s, ip=%(ip)s",
                            {'host': host_id, 'if': interface,
                             'ip': nexus_ip})
  
      return mapping
docs: Add Host to interface mapping entry into mapping data base.
  
      :param host_id: is the name of the host to add
      :param interface: is the interface for this host
      :param nexus_ip: is the ip addr of the nexus switch for this interface
      :param ch_grp: is the port channel this interface belos
      :param is_static: whether this is from conf file or learned from baremetal.