Gets the last component of the filename. If file_name ends with a
directory separator it gets the component before the last slash. If
file_name consists only of directory separators (and on Windows,
possibly a drive letter), a single separator is returned. If
file_name is empty, it gets ".".
Gets the last component of the filename. If file_name ends with a directory separator it gets the component before the last slash. If file_name consists only of directory separators (and on Windows, possibly a drive letter), a single separator is returned. If file_name is empty, it gets ".".