editIssue(issue, issueData, cb) {
      return this._request('PATCH', `/repos/${this.__repository}/issues/${issue}`, issueData, cb);
   }
Edit an issue
@see https://developer.github.com/v3/issues/#edit-an-issue
@param {number} issue - the issue number to edit
@param {Object} issueData - the new issue data
@param {Requestable.callback} [cb] - will receive the modified issue
@return {Promise} - the promise for the http request