func resizeBuffer(b1 []byte, size int) []byte {
	if b1 == nil || cap(b1) < size {
		b2 := make([]byte, size)
		copy(b2, b1) // !!!
		return b2
	}
	return b1[:size]
}
func resizeBuffer(b1 []byte, size int) []byte {
	if b1 == nil || cap(b1) < size {
		b2 := make([]byte, size)
		copy(b2, b1) 
		return b2
	}
	return b1[:size]
}
func resizeBuffer ( b1 [ ] byte , size int ) [ ] byte { if b1 == nil || cap ( b1 ) < size { b2 := make ( [ ] byte , size ) copy ( b2 , b1 ) // !!! return b2 } return b1 [ : size ] }
// helper
helper