code: func (l *Line) Copy() *Line {
  	nl := *l
  	nl.Args = make([]string, len(l.Args))
  	copy(nl.Args, l.Args)
  	if l.Tags != nil {
  		nl.Tags = make(map[string]string)
  		for k, v := range l.Tags {
  			nl.Tags[k] = v
  		}
  	}
  	return &nl
  }
docs: // Copy returns a deep copy of the Line.