code: func (ba *bitArray) Nand(other BitArray) BitArray {
  	if dba, ok := other.(*bitArray); ok {
  		return nandDenseWithDenseBitArray(ba, dba)
  	}
  
  	return nandDenseWithSparseBitArray(ba, other.(*sparseBitArray))
  }
docs: // Nand will return the result of doing a bitwise and not of the bit array
  // with the other bit array on each block.