code: function toKey(value) {
    if (typeof value == 'string' || isSymbol(value)) {
      return value;
    }
    var result = (value + '');
    return (result == '0' && (1 / value) == -INFINITY$2) ? '-0' : result;
  }
docs: Converts `value` to a string key if it's not a string or symbol.
  
  @private
  @param {*} value The value to inspect.
  @returns {string|symbol} Returns the key.