code: func removePKCSPadding(src []byte) ([]byte, error) {
  	length := len(src)
  	padLength := int(src[length-1])
  	if padLength > aes.BlockSize || length < aes.BlockSize {
  		return nil, errInvalidPadding
  	}
  
  	return src[:length-padLength], nil
  }
docs: // removePKCSPadding removes padding from data that was added with addPKCSPadding