"use strict";

function mandatory(paramName) {
  throw new Error(`Missing parameter: ${paramName}`);
}

function foo(_x) {
  return _foo.apply(this, arguments);
}

function _foo() {
  _foo = babelHelpers.asyncToGenerator(function* (_ref) {
    let a = _ref.a,
        _ref$b = _ref.b,
        b = _ref$b === void 0 ? mandatory("b") : _ref$b;
    return Promise.resolve(b);
  });
  return _foo.apply(this, arguments);
}