function parseSimpleNumbers (parser) {
  const length = parser.buffer.length - 1;
  var offset = parser.offset;
  var number = 0;
  var sign = 1;

  if (parser.buffer[offset] === 45) {
    sign = -1;
    offset++;
  }

  while (offset < length) {
    const c1 = parser.buffer[offset++];
    if (c1 === 13) { // \r\n
      parser.offset = offset + 1;
      return sign * number
    }
    number = (number * 10) + (c1 - 48);
  }
}
Used for integer numbers only
@param {JavascriptRedisParser} parser
@returns {undefined|number}