code: func (c *Manager) ListLibraries(ctx context.Context) ([]string, error) {
  	url := internal.URL(c, internal.LibraryPath)
  	var res []string
  	return res, c.Do(ctx, url.Request(http.MethodGet), &res)
  }
docs: // ListLibraries returns a list of all content library IDs in the system.