code: def test_empty_c_code():
      code_gen = C89CodeGen()
      source = get_string(code_gen.dump_c, [])
      assert source == '#include "file.h"\n#include <math.h>\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 3 for calling a global function with example usage: test_empty_c_code() without return types