doc/issue-service/sample.js
function tagIssue (client, repo, number, label) {
  return client.addLabel(repo, number, label).then(convertIssue);
}
function tagIssue (client, repo, number, label) {
  return client.addLabel(repo, number, label).then(convertIssue);
}
function tagIssue ( client , repo , number , label ) { return client . addLabel ( repo , number , label ) . then ( convertIssue ) ; }
Assuming client.addLabel returns a promise of issue
Assuming client . addLabel returns a promise of issue