code: def test_stack():
      axis = 2
      layer = dc.models.layers.Stack(axis=axis)
      config = layer.get_config()
      layer_copied = dc.models.layers.Stack.from_config(config)
  
      assert layer_copied.axis == layer.axis
  
imports: import deepchem
  import pytest
label_desc: Use image node_id 11 for calling a global function with example usage: test_stack() without return types