node_modules/underscore.string/toSentence.js

var rtrim = require('./rtrim');

module.exports = function toSentence(array, separator, lastSeparator, serial) {
  separator = separator || ', ';
  lastSeparator = lastSeparator || ' and ';
  var a = array.slice(),
    lastMember = a.pop();

  if (array.length > 2 && serial) lastSeparator = rtrim(separator) + lastSeparator;

  return a.length ? a.join(separator) + lastSeparator + lastMember : lastMember;
};