code: def test_mat_generator():
      """Test invoking MATGenerator."""
      torch.manual_seed(0)
      input_ar = torch.tensor([1.0, 2.0, 3.0])
      layer = torch_layers.MATGenerator(3, "mean", 1, 1, 0.0)
      mask = torch.tensor([1.0, 1.0, 1.0])
      result = layer(input_ar, mask)
      output_ar = torch.tensor([-1.4436])
      assert torch.allclose(result, output_ar, rtol=1e-4)
  
imports: import deepchem
  import numpy
  import pytest
  import os
label_desc: Use image node_id 38 for calling a global function with example usage: test_mat_generator() without return types