docs: function processScalarParam(existedParam: Object, value: Object): Object {
    if (Array.isArray(existedParam)) {
      // value is already an array, so push on the next value.
      existedParam.push(value);
      return existedParam;
    }
    if (existedParam !== undefined) {
      // value isn't an array, but since a second value has been specified,
      // convert value into an array.
      return [existedParam, value];
    }
    // value is a scalar.
    return value;
  }