code: def p_tag_ref(self, p):
          'tag_ref : ID'
          p[0] = AstTagRef(self.path, p.lineno(1), p.lexpos(1), p[1]f p_tag_ref(self, p):
          'tag_ref : ID'
          p[0] = AstTagRef(self.path, p.lineno(1), p.lexpos(1), p[1])
docs: tag_ref : ID