code: def test_abs_fallback_expr():
      expr = ast.AbsExpr(ast.NumVal(-2.0))
  
      interpreter = CInterpreter()
      interpreter.abs_function_name = NotImplemented
  
      expected_code = """
  double score(double * input) {
      double var0;
      double var1;
      var1 = -2.0;
      if (var1 < 0.0) {
          var0 = 0.0 - var1;
      } else {
          var0 = var1;
      }
      return var0;
  }
  """
  
      assert_code_equal(interpreter.interpret(expr), expected_code)
  
file_path: m2cgen/tests/test_fallback_expressions.py
imports: import pytest
  from m2cgen import ast
  from m2cgen.interpreters import CInterpreter, PythonInterpreter
  from tests.utils import assert_code_equal
label_desc: Use image node_id 2 for calling a global function with example usage: test_abs_fallback_expr() without return types