docs: function buildOpts (keys) {
    var opts = {}
    var pairs = _.pairs(keys)
    for (var i in pairs) {
      var argvKey = pairs[i][0]
      var envKey = argvKey.toUpperCase()
      var configKey = pairs[i][1]
      opts[configKey] = argv[argvKey] || config.get(configKey)
      if (opts[configKey] === null) {
        throw Error("The environment variable '" + envKey + "', or command line parameter '--" + argvKey + "' must be set.")
      }
    }
    return opts
  }