whole_func_string: function registerApi(apiConfig) {
      let baseApi = base.$api;
      apiConfig && Object.keys(apiConfig).forEach(k => {
          // TODO: when in dev mode, warn the existed API will be override
          definePropertyValue(baseApi, k, apiConfig[k]);
      });
  }
func_code_string: function registerApi(apiConfig) {
      let baseApi = base.$api;
      apiConfig && Object.keys(apiConfig).forEach(k => {
          // TODO: when in dev mode, warn the existed API will be override
          definePropertyValue(baseApi, k, apiConfig[k]);
      });
  }
func_documentation_string: Register API
  
  @param {Object} apiConfig the api config to register