code: def p_const_ref(self, p):
          '''const_ref : IDENTIFIER'''
          p[0] = ast.ConstReference(p[1], lineno=p.lineno(1)f p_const_ref(self, p):
          '''const_ref : IDENTIFIER'''
          p[0] = ast.ConstReference(p[1], lineno=p.lineno(1))
docs: const_ref : IDENTIFIER