code: func leftPad(input []byte, size int) (out []byte) {
  	n := len(input)
  	if n > size {
  		n = size
  	}
  	out = make([]byte, size)
  	copy(out[len(out)-n:], input)
  	return
  }
docs: // leftPad returns a new slice of length size. The contents of input are right
  // aligned in the new slice.