code: def test_ansi_math2_codegen():
      # not included: frexp, ldexp, modf, fmod
      from sympy.functions.elementary.trigonometric import atan2
  
      x, y = symbols("x,y")
      name_expr = [
          ("test_atan2", atan2(x, y)),
          ("test_pow", x**y),
      ]
      result = codegen(
          name_expr, "C89", "file", header=False, empty=False
      )
      assert result[0][0] == "file.c"
      assert result[0][1] == (
          '#include "file.h"\n#include <math.h>\n'
          "double test_atan2(double x, double y) {\n   double test_atan2_result;\n   test_atan2_result = atan2(x, y);\n   return test_atan2_result;\n}\n"
          "double test_pow(double x, double y) {\n   double test_pow_result;\n   test_pow_result = pow(x, y);\n   return test_pow_result;\n}\n"
      )
      assert result[1][0] == "file.h"
      assert result[1][1] == (
          "#ifndef PROJECT__FILE__H\n#define PROJECT__FILE__H\n"
          "double test_atan2(double x, double y);\n"
          "double test_pow(double x, double y);\n"
          "#endif\n"
      )
  
imports: from io import StringIO
  from sympy.core import symbols, Eq, pi, Catalan, Lambda, Dummy
  from sympy.core.relational import Equality
  from sympy.core.symbol import Symbol
  from sympy.functions.special.error_functions import erf
  from sympy.integrals.integrals import Integral
  from sympy.matrices import Matrix, MatrixSymbol
  from sympy.utilities.codegen import codegen, make_routine, CCodeGen, C89CodeGen, C99CodeGen, InputArgument, CodeGenError, FCodeGen, CodeGenArgumentListError, OutputArgument, InOutArgument
  from sympy.testing.pytest import raises
  from sympy.utilities.lambdify import implemented_function
label_desc: Use image node_id 15 for calling a global function with example usage: test_ansi_math2_codegen() without return types