code: func (f HeaderExtension) EntrySize() int {
  	// Length of the name includes a null terminator
  	// the 4 * 5 is 4 bytes (uint32) for the 5 fields
  	baseSize := f.FileEntry.EntrySize()
  
  	for key, val := range f.ExtendedFields {
  		// + 2 for the null terminator for each key/val
  		baseSize += len(key) + len(val) + 2
  	}
  
  	// There's a null terminator at the end of the block
  	return baseSize + 1
  }
docs: // Gets the length of the entry block