code: func (s *IssuesService) Get(ctx context.Context, owner string, repo string, number int) (*Issue, *Response, error) {
  	u := fmt.Sprintf("repos/%v/%v/issues/%d", owner, repo, number)
  	req, err := s.client.NewRequest("GET", u, nil)
  	if err != nil {
  		return nil, nil, err
  	}
  
  	// TODO: remove custom Accept headers when APIs fully launch.
  	acceptHeaders := []string{mediaTypeReactionsPreview, mediaTypeLabelDescriptionSearchPreview, mediaTypeLockReasonPreview}
  	req.Header.Set("Accept", strings.Join(acceptHeaders, ", "))
  
  	issue := new(Issue)
  	resp, err := s.client.Do(ctx, req, issue)
  	if err != nil {
  		return nil, resp, err
  	}
  
  	return issue, resp, nil
  }
docs: // Get a single issue.
  //
  // GitHub API docs: https://developer.github.com/v3/issues/#get-a-single-issue