code: def test_default_sort_key():
      func = lambda x: x
      assert sorted([func, x, func], key=default_sort_key) == [
          func,
          func,
          x,
      ]
  
      class C:
          def __repr__(self):
              return "x.y"
  
      func = C()
      assert sorted([x, func], key=default_sort_key) == [func, x]
  
imports: from sympy.core.sorting import default_sort_key, ordered
  from sympy.testing.pytest import raises
  from sympy.abc import x
label_desc: Use image node_id 1 for calling a global function with example usage: test_default_sort_key() and returns: str