function toKey(value) {
  if (typeof value == 'string' || Object(_isSymbol_js__WEBPACK_IMPORTED_MODULE_0__[/* default */ "a"])(value)) {
    return value;
  }
  var result = (value + '');
  return (result == '0' && (1 / value) == -INFINITY) ? '-0' : result;
}
Used to compose unicode character classes.