clean_code_vertical2.js

  const sizeDifference    = _(proposals).size() - _(userAnswers).size(); // 2
  const completeWithFalse = _.times(sizeDifference, _.constant(false));  // [false, false]

  return  _.chain(userAnswers)           // [false, true]
            .concat(completeWithFalse)   // [false, true, false, false]
            .zip(proposals)              // [[false, 'prop 1'], [true, 'prop 2'], [false, 'prop 3'], [false, 'prop 4']]
            .map(_.reverse)              // [['prop 1', false], ['prop 2', true], ['prop 3', false], ['prop 4', false]]
            .value();