nodes: 0, module; 1, function_definition; 2, function_name:_get_sorting_key_values; 3, parameters; 4, block; 5, identifier:self; 6, identifier:array1; 7, identifier:array2; 8, expression_statement; 9, expression_statement; 10, expression_statement; 11, return_statement; 12, comment:"""return the sorting key values as a series"""; 13, assignment; 14, assignment; 15, call; 16, identifier:concat_arrays; 17, call; 18, identifier:unique_values; 19, call; 20, attribute; 21, argument_list; 22, attribute; 23, argument_list; 24, attribute; 25, argument_list; 26, identifier:numpy; 27, identifier:sort; 28, identifier:unique_values; 29, identifier:numpy; 30, identifier:concatenate; 31, list; 32, identifier:numpy; 33, identifier:unique; 34, identifier:concat_arrays; 35, identifier:array1; 36, identifier:array2
code: def _get_sorting_key_values(self, array1, array2):
          """return the sorting key values as a series"""
  
          concat_arrays = numpy.concatenate([array1, array2])
          unique_values = numpy.unique(concat_arrays)
  
          return numpy.sort(unique_values)