'use strict'; var tryToString = require('../internals/try-to-string'); var $TypeError = TypeError; // Perform ? RequireInternalSlot(M, [[SetData]]) module.exports = function (it) { if (typeof it == 'object' && 'size' in it && 'has' in it && 'add' in it && 'delete' in it && 'keys' in it) return it; throw new $TypeError(tryToString(it) + ' is not a set'); };