code: def test_get_pure_function():
      from deepchem.utils.differentiation_utils import get_pure_function
  
      def fcn(x, y):
          return x + y
  
      pfunc = get_pure_function(fcn)
      assert pfunc(1, 2) == 3
  
imports: import pytest
label_desc: Use image node_id 35 for calling a global function with example usage: test_get_pure_function() and returns: unknown