code: func (opt Option) Copy(p []byte) Option {
  	n := copy(p, opt.Name)
  	opt.Name = p[:n]
  	opt.Parameters, p = opt.Parameters.Copy(p[n:])
  	return opt
  }
docs: // Copy copies all underlying []byte slices into p and returns new Option.
  // Note that p must be at least of opt.Size() length.