list.go
func (l List) String() string {
	buf := pool.AllocBuffer()
	defer pool.ReleaseBuffer(buf)
	l.writeToBuffer(buf)
	return buf.String()
}
func (l List) String() string {
	buf := pool.AllocBuffer()
	defer pool.ReleaseBuffer(buf)
	l.writeToBuffer(buf)
	return buf.String()
}
// String returns a string representation of the key/value pairs in
// logfmt format: "key1=value1 key2=value2  ...".