bin/ysh is the shell with data tYpes, influenced by pYthon, JavaScript, ...

Usage: ysh FLAG* SCRIPT ARG*
       ysh FLAG* -c COMMAND ARG*
       ysh FLAG*

Examples:

    ysh -c 'echo hi'
    ysh myscript.ysh
    echo 'echo hi' | ysh

bin/ysh is the same as bin/osh with a the ysh:all option group set.  So bin/ysh
also accepts shell flags.  Examples:

    bin/ysh -n myfile.ysh
    bin/ysh +o errexit -c 'false; echo ok'
