code: func findSequence(head *sequence, bytePos uint64) (*sequence, *sequence, uint64, uint64) {
  	// Find the sequence containing this byte
  	previous := head
  	current := head
  	n := bytePos
  	for current.next != nil && n >= (current.count*blockBytes) { // Nil check for less than 32 addresses masks
  		n -= (current.count * blockBytes)
  		previous = current
  		current = current.next
  	}
  
  	// If byte is outside of the list, let caller know
  	if n >= (current.count * blockBytes) {
  		return nil, nil, 0, invalidPos
  	}
  
  	// Find the byte position inside the block and the number of blocks
  	// preceding the block containing the byte inside this sequence
  	precBlocks := n / blockBytes
  	inBlockBytePos := bytePos % blockBytes
  
  	return current, previous, precBlocks, inBlockBytePos
  }
docs: // Given the byte position and the sequences list head, return the pointer to the
  // sequence containing the byte (current), the pointer to the previous sequence,
  // the number of blocks preceding the block containing the byte inside the current sequence.
  // If bytePos is outside of the list, function will return (nil, nil, 0, invalidPos)