const getOptimizationTypeFromQueryString = queryString => {
  if (!queryString['opt']) {
    return 'aggressive'
  } else if (queryString['opt'] == 'none') {
    return 'none'
  } else if (queryString['opt'] == 'mild') {
    return 'mild'
  } else if (queryString['opt'] == 'aggressive') {
    return 'aggressive'
  } else {
    DEBUG && console.log("Couldn't understand opt parameter's value. Going to do" +
      " aggressive optimization")
    return 'aggressive'
  }
}