args.go
func (a *Args) PeekBytes(key []byte) []byte {
	return peekArgBytes(a.args, key)
}
func (a *Args) PeekBytes(key []byte) []byte {
	return peekArgBytes(a.args, key)
}
// PeekBytes returns query arg value for the given key.
//
// Returned value is valid until the next Args call.