code: func (h Headers) String() string {
  	ec := h.Validate()
  	if ec != nil {
  		return ec.Error()
  	}
  	b := make([]byte, 0, 1024)
  	for i := 0; i < len(h); i += 2 {
  		b = append(b, h[i]+":"+h[i+1]+"\n"...)
  	}
  	return string(b)
  }
docs: /*
  	String makes Headers a Stringer.
  */