code: func (s *SiteInfo) Param(key interface{}) (interface{}, error) {
  	keyStr, err := cast.ToStringE(key)
  	if err != nil {
  		return nil, err
  	}
  	keyStr = strings.ToLower(keyStr)
  	return s.Params()[keyStr], nil
  }
docs: // Param is a convenience method to do lookups in SiteInfo's Params map.
  //
  // This method is also implemented on Page and Node.