code: function handleCallback(callback, err, httpResponse, body) {
  
      if(err){
          return callback(err);
      }
  
      //
      // API returns error
      //
      if( body.status !== 'OK' ){
          return callback(new Error(body.comment));
      }
  
      return callback(null, body.result);
  }
docs: Handle user callback
  
  @param callback - user callback
  @param err - request errors
  @param httpResponse - request HTTP response
  @param body - request response body
  @returns {*}