/**
   * Adds the key-value `pair` to `map`.
   *
   * @private
   * @param {Object} map The map to modify.
   * @param {Array} pair The key-value pair to add.
   * @returns {Object} Returns `map`.
   */
  function addMapEntry(map, pair) {
    // Don't return `map.set` because it's not chainable in IE 11.
    map.set(pair[0], pair[1]);
    return map;
  }
  
  module.exports = addMapEntry;