docs: function generateMessengerCode(options) {
    return new Promise (async (resolve, reject) => {
      let request_options = {
        'path': '/me/messenger_codes',
        'payload': {
          'type': 'standard'
        }
      };
  
      if (options.ref) request_options.payload.data = {'ref': options.ref};
      if (options.image_size) {
        if (options.image_size < 100 || options.image_size > 2000) {
          reject('image_size must be between 100-2000.');        
        }
        request_options.payload.image_size = options.image_size;
      }
  
      try {
        let response = await this.sendGraphRequest(request_options);
        resolve(response);
      } catch (e) {
        reject(e);
      }    
    });
  }