code: def test_mxmnet_envelope():
      """Test for _MXMNetEnvelope helper layer."""
      env = dc.models.torch_models.layers._MXMNetEnvelope(exponent=2)
      input_tensor = torch.tensor([0.5, 1.0, 2.0, 3.0])
      output = env(input_tensor)
      output = output.detach().numpy()
      result = np.array([1.3125, 0.0000, 0.0000, 0.0000])
      assert np.allclose(result, output, atol=1e-04)
  
imports: import deepchem
  import numpy
  import pytest
  import os
label_desc: Use image node_id 53 for calling a global function with example usage: test_mxmnet_envelope() without return types