filePrefix method
Extracts the portion of the file name before the first "." -
None, if there is no file name; The entire file name if there is no embedded .; The portion of the file name before the first non-beginning .; The entire file name if the file name begins with . and has no other .s within; The portion of the file name before the second . if the file name begins with .
Implementation
Option<String> filePrefix() =>
isWindows ? WindowsPath(_string).filePrefix() : UnixPath(_string).filePrefix();