code: def eval_expression(self, t):
          
          t = CPP_to_Python(' '.join(t[1:]))
          try: return eval(t, self.cpp_namespace)
          except (NameError, TypeError): return 0
docs: Evaluates a C preprocessor expression.
  
          This is done by converting it to a Python equivalent and
          eval()ing it in the C preprocessor namespace we use to
          track #define values.