code: func (s *AppsService) ListRepos(ctx context.Context, opt *ListOptions) ([]*Repository, *Response, error) {
  	u, err := addOptions("installation/repositories", opt)
  	if err != nil {
  		return nil, nil, err
  	}
  
  	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", mediaTypeIntegrationPreview)
  
  	var r struct {
  		Repositories []*Repository `json:"repositories"`
  	}
  	resp, err := s.client.Do(ctx, req, &r)
  	if err != nil {
  		return nil, resp, err
  	}
  
  	return r.Repositories, resp, nil
  }
docs: // ListRepos lists the repositories that are accessible to the authenticated installation.
  //
  // GitHub API docs: https://developer.github.com/v3/apps/installations/#list-repositories