code: def _mask(valid, total):
      return np.repeat([True, False], (valid, total - valid))
  
imports: from stellargraph.core.graph import *
  from stellargraph.mapper.padded_graph_generator import PaddedGraphGenerator, PaddedGraphSequence
  import numpy
  import pytest
  from ..test_utils.graphs import example_graph_random, example_graph, example_hin_1
label_desc: Use image node_id 1 for calling a global function with example usage: _mask(valid, total) and returns: np