code: def namedb_name_import_sanity_check( cur, opcode, op_data, history_id, block_id, vtxindex, prior_import, record_table):
      
  
      assert opcode in OPCODE_NAME_STATE_IMPORTS, "BUG: opcode '%s' does not import a name" % (opcode)
      assert record_table == "name_records", "BUG: wrong table %s" % record_table
      assert namedb_is_history_snapshot( op_data ), "BUG: import is incomplete"
      
      namedb_op_sanity_check( opcode, op_data, op_data )
  
      # must be the only such existant name, if prior_import is None
      name_rec = namedb_get_name( cur, history_id, block_id )
      if prior_import is None:
          assert name_rec is None, "BUG: trying to import '%s' for the first time, again" % history_id
      else:
          assert name_rec is not None, "BUG: trying to overwrite non-existent import '%s'" % history_id
          assert prior_import['name'] == history_id, "BUG: trying to overwrite import for different name '%s'" % history_id
          
          # must actually be prior
          assert prior_import['block_number'] < block_id or (prior_import['block_number'] == block_id and prior_import['vtxindex'] < vtxindex), \
                  "BUG: prior_import comes after op_data"
  
      return True
docs: Sanity checks on a name-import:
      * the opcode must match the op_data
      * everything must match the record table.
      * if prior_import is None, then the name shouldn't exist
      * if prior_import is not None, then it must exist
  
      Return True on success
      Raise an exception on error.
  
      DO NOT CALL THIS METHOD DIRECTLY.