writeFromSync method
override
    Synchronously writes from a buffer to the file.
Will read the buffer from index start to index end.
The start must be non-negative and no greater than buffer.length.
If end is omitted, it defaults to buffer.length.
Otherwise end must be no less than start
and no greater than buffer.length.
Throws a FileSystemException if the operation fails.
Implementation
@override
void writeFromSync(List<int> buffer, [int start = 0, int? end]) =>
    delegate.writeFromSync(buffer, start, end);