code: function checkout (cb) {
      if (my.args.length !== 1) {
        return cb( erf( '"checkout" command requires single <bin> argument' ) )
      }
      var bin
      , found = false
      , chbin = my.args[0]
  
      for (bin in my.state.bins) {
        if (path.basename(bin) === path.basename(chbin)) {
          my.state.bins = setActiveBin(my.state.bins, bin)
          found = true
        }
      }
      if (!found) {
        return cb( erf( 'Can not checkout ' +  path.basename(chbin)
                        + '. Bin not recognized'))
      }
      cb(null, my.state)
    }
docs: ###### CHECKOUT ######