doc/issue-service/sample.js
function commentIssue (client, repo, number, comment) {
  return client.createComment(repo, number, comment).then(convertComment);
}
function commentIssue (client, repo, number, comment) {
  return client.createComment(repo, number, comment).then(convertComment);
}
function commentIssue ( client , repo , number , comment ) { return client . createComment ( repo , number , comment ) . then ( convertComment ) ; }
Assuming client.createComment returns a promise of comment
Assuming client . createComment returns a promise of comment