Can't use --stdin option about sassc HOT 1 CLOSED

# sassc --version
sassc: 3.0.2-14-g65d2
libsass: 3.0.2-147-g4efc-dirty
sass2scss: 1.0.3

# sassc --help
Usage: sassc [options] [INPUT] [OUTPUT]

Options:
   -s, --stdin             Read input from standard input instead of an input file.
   -t, --style NAME        Output style. Can be: nested, compressed.
   -l, --line-numbers      Emit comments showing original line numbers.
       --line-comments
   -I, --load-path PATH    Set Sass import path.
   -m, --sourcemap         Emit source map.
   -M, --omit-map-comment  Omits the source map url comment.
   -p, --precision         Set the precision for numbers.
   -v, --version           Display compiled versions.
   -h, --help              Display this help message.