measure.go
func NewMeasuredWriter(w io.Writer) *MeasuredWriter {
	return &MeasuredWriter{wrap: w, rate: newCounter()}
}
func NewMeasuredWriter(w io.Writer) *MeasuredWriter {
	return &MeasuredWriter{wrap: w, rate: newCounter()}
}
func NewMeasuredWriter ( w io . Writer ) * MeasuredWriter { return & MeasuredWriter { wrap : w , rate : newCounter ( ) } }
// NewMeasuredWriter wraps a writer.
NewMeasuredWriter wraps a writer .