code: func (s *RepositoriesService) GetPullRequestReviewEnforcement(ctx context.Context, owner, repo, branch string) (*PullRequestReviewsEnforcement, *Response, error) {
  	u := fmt.Sprintf("repos/%v/%v/branches/%v/protection/required_pull_request_reviews", owner, repo, branch)
  	req, err := s.client.NewRequest("GET", u, nil)
  	if err != nil {
  		return nil, nil, err
  	}
  
  	// TODO: remove custom Accept header when this API fully launches
  	req.Header.Set("Accept", mediaTypeRequiredApprovingReviewsPreview)
  
  	r := new(PullRequestReviewsEnforcement)
  	resp, err := s.client.Do(ctx, req, r)
  	if err != nil {
  		return nil, resp, err
  	}
  
  	return r, resp, nil
  }
docs: // GetPullRequestReviewEnforcement gets pull request review enforcement of a protected branch.
  //
  // GitHub API docs: https://developer.github.com/v3/repos/branches/#get-pull-request-review-enforcement-of-protected-branch