code: def test_function_call():
      def square(x):
          return np.sum(x**2)
  
      assert square(2) == 4
  
      def square2(x, y):
          return x**2 + y**2
  
      assert square2(2, 2) == 8
  
      new_function = function.Function(square)
  
      assert new_function(np.zeros(2)) == 0
  
      try:
          new_function = function.Function(square2)
      except:
          new_function = function.Function(square)
  
      assert new_function.name == "square"
  
file_path: opytimizer/tests/opytimizer/core/test_function.py
imports: import numpy
  from opytimizer.core import function
  from opytimizer.utils import constant
label_desc: Use image node_id 8 for calling a global function with example usage: test_function_call() and returns: np, unknown