$ ./example/example.sh usage
coal example - coal example application version 1.0.0 (https://github.com/zeriyoshi/coal)

Usage:
    ./example/example.sh [command]

Commands:
    foo                 foo - blah blah blah
    bar                 bar - nest example
    baz                 baz - external nest example
    posix_getopt        posix_getopt - getopt sample (--test=<value>)
    argument_parser     argument_parser - argument parsing example
    config              config - config example ([key] --set=<value>)