arguments.go
func NewArgWriter(writer io.WriteCloser, err error) ArgWriteHelper {
	return ArgWriteHelper{writer, err}
}
func NewArgWriter(writer io.WriteCloser, err error) ArgWriteHelper {
	return ArgWriteHelper{writer, err}
}
// NewArgWriter wraps the result of calling ArgXWriter to provider a simpler
// interface for writing arguments.