code: func IsAttachedTrytes(trytes Trytes) bool {
  	return IsTrytesOfExactLength(trytes, TransactionTrytesSize) && !IsEmptyTrytes(trytes[(TransactionTrytesSize)-3*HashTrytesSize:])
  }
docs: // IsAttachedTrytes checks if input is valid attached transaction trytes.
  // For attached transactions the last 243 trytes are non-zero.