code: def test_cosm1():
      cm1_xy = cosm1(x * y)
      ref_xy = cos(x * y) - 1
      for wrt, deriv_order in product([x, y, z], range(3)):
          assert (
              cm1_xy.diff(wrt, deriv_order)
              - ref_xy.diff(wrt, deriv_order)
          ).rewrite(cos).simplify() == 0
  
      expr_minus2 = cosm1(pi)
      assert expr_minus2.rewrite(cos) == -2
      assert cosm1(3.14).simplify() == cosm1(
          3.14
      )  # cannot simplify with 3.14
      assert cosm1(pi / 2).simplify() == -1
      assert (1 / cos(x) - 1 + cosm1(x) / cos(x)).simplify() == 0
  
file_path: sympy/sympy/codegen/tests/test_scipy_nodes.py
imports: from itertools import product
  from sympy.core.power import Pow
  from sympy.core.symbol import symbols
  from sympy.functions.elementary.exponential import exp, log
  from sympy.functions.elementary.trigonometric import cos
  from sympy.core.numbers import pi
  from sympy.codegen.scipy_nodes import cosm1, powm1
label_desc: Use image node_id 1 for calling a global function with example usage: test_cosm1() without return types