function escaping(index, count) {
  while (--count && next()) {
    // not 0-9 A-F a-f
    if (character < 48 || character > 102 || character > 57 && character < 65 || character > 70 && character < 97) break;
  }

  return slice(index, caret() + (count < 6 && peek() == 32 && next() == 32));
}
@param {number} index
@param {number} count
@return {string}