arg was not defined. Might be a silly typo

Kept throwing 

    ~/Projects/Git/Github/webtorrent/bin/cmd.js:57
        ? arg.omx + ' '
        ^
    ReferenceError: arg is not defined
        at Object.<anonymous> (/home/shyam/Projects/Git/Github/webtorrent/bin/cmd.js:57:5)
        at Module._compile (module.js:456:26)
        at Object.Module._extensions..js (module.js:474:10)
        at Module.load (module.js:356:32)
        at Function.Module._load (module.js:312:12)
        at Function.Module.runMain (module.js:497:10)
        at startup (node.js:119:16)
        at node.js:902:3`