Question: I am new the Python 3.7 and I am trying to read bytes from a serial port using the following code. I am using `pySerial` module and the [read()](https://pyserial.readthedocs.io/en/latest/pyserial_api.html#serial.Serial.read) function returns `bytes`. 

```
self.uart = serial.Serial()
self.uart.port = '/dev/tty/USB0'
self.uart.baudrate = 115200
self.uart.open()
# buffer for received bytes
packet_bytes = bytearray()
# read and process data from serial port
while True:
    # read single byte from serial port
    current_bytes = self._uart.read()
    if current_bytes is B'$':
        self.process_packet(packet_bytes)
        packet_bytes = bytearray()
    else:
        packet_bytes.append(current_bytes)        <- Error occurs here

```

I receive the following error:

> 
> TypeError: an integer is required
> 
> 
> 

Some idea how to solve?

Answer: 
```
packet_bytes += bytearray(current_bytes)

```
I recently had this problem myself and this is what worked for me. Instead of instantiating a bytearray, I just initialized my buffer as a byte object:

```
buf = b""    #Initialize byte object

  poll = uselect.poll()
  poll.register(uart, uselect.POLLIN)

  while True:
    ch = uart.read(1) if poll.poll() else None

    if ch == b'x':
      buf += ch       #append the byte character to the buffer

    if ch == b'y':
      buf = buf[:-1]  #remove the last byte character from the buffer

    if ch == b'\015': ENTER
      break

```