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