code: func (j *TableJoin) HandlesFieldName(fieldName string) bool {
  	for _, t := range j.PrefixActivators {
  		if strings.HasPrefix(fieldName, t) {
  			return true
  		}
  	}
  	return false
  }
docs: // HandlesFieldName returns true if the given field name should be handled by
  // this table join.