docstr: 判断是否是某种框架的 backend
  
  :return:
docstr_tok: ["\u5224\u65ad\u662f\u5426\u662f\u67d0\u79cd\u6846\u67b6\u7684","backend",":","return",":"]
code: def is_specified(self) -> bool:
      """
      判断是否是某种框架的 backend
  
      :return:
      """
      return self._specified
  
file_path: fastNLP/fastNLP/core/metrics/backend/jittor_backend/backend.py
imports: import numpy
  from fastNLP.envs.imports import _NEED_IMPORT_JITTOR
  from fastNLP.core.metrics.backend import Backend
label_desc: Use image node_id 6 for calling the JittorBackend obj's underlying member method code with example usage: obj.is_specified() and returns: self