code: func (args Args) Clone() (newArgs Args) {
  	newArgs.fields = make(map[string]map[string]bool, len(args.fields))
  	for k, m := range args.fields {
  		var mm map[string]bool
  		if m != nil {
  			mm = make(map[string]bool, len(m))
  			for kk, v := range m {
  				mm[kk] = v
  			}
  		}
  		newArgs.fields[k] = mm
  	}
  	return newArgs
  }
docs: // Clone returns a copy of args.