code: func (a *Args) merge(r *Args) Args {
  	out := Args{
  		Values: make([]Arg, len(a.Values)),
  		Elided: a.Elided,
  	}
  	for i, l := range a.Values {
  		if l != r.Values[i] {
  			out.Values[i].Name = "*"
  			out.Values[i].Value = l.Value
  		} else {
  			out.Values[i] = l
  		}
  	}
  	return out
  }
docs: // merge merges two similar Args, zapping out differences.