RE: Transferring Python2 to Python3 on This Specific Line - python-3.x

Question

I am attempting to change this line to become acceptable by python3 from a python2 set of source:
Here is the error:
TypeError: unicode strings are not supported, please encode to bytes:
'$PMTK251,9600*17\r\n'
Can anyone tell my why this is this way or how I can change it to suit Python3 methods?
It is a GPS set of source in Python2 that still works but I see that all ideas relating to Python2 will be gone from availability and/or is already pretty much done and gone.
So, my ideas were to update that line and others.
In python3, I receive errors relating to bytes and I have currently read about the idea of (arg, newline='') in source when attempting to make .csv files in Python3.
I am still at a loss w/ how to incorporate Python3 in this specific line.
I can offer more about the line or the rest of the source if necessary. I received this source from toptechboy.com. I do not think that fellow ever updated the source to work w/ Python3.
class GPS:
def __init__(self):
#This sets up variables for useful commands.
#This set is used to set the rate the GPS reports
UPDATE_10_sec = "$PMTK220,10000*2F\r\n" #Update Every 10 Seconds
UPDATE_5_sec = "$PMTK220,5000*1B\r\n" #Update Every 5 Seconds
UPDATE_1_sec = "$PMTK220,1000*1F\r\n" #Update Every One Second
UPDATE_200_msec = "$PMTK220,200*2C\r\n" #Update Every 200 Milliseconds
#This set is used to set the rate the GPS takes measurements
MEAS_10_sec = "$PMTK300,10000,0,0,0,0*2C\r\n" #Measure every 10 seconds
MEAS_5_sec = "$PMTK300,5000,0,0,0,0*18\r\n" #Measure every 5 seconds
MEAS_1_sec = "$PMTK300,1000,0,0,0,0*1C\r\n" #Measure once a second
MEAS_200_msec= "$PMTK300,200,0,0,0,0*2F\r\n" #Meaure 5 times a second
#Set the Baud Rate of GPS
BAUD_57600 = "$PMTK251,57600*2C\r\n" #Set Baud Rate at 57600
BAUD_9600 ="$PMTK251,9600*17\r\n" #Set 9600 Baud Rate
#Commands for which NMEA Sentences are sent
ser.write(BAUD_57600)
sleep(1)
ser.baudrate = 57600
GPRMC_ONLY = "$PMTK314,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0*29\r\n" #Send only the GPRMC Sentence
GPRMC_GPGGA = "$PMTK314,0,1,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0*28\r\n"#Send GPRMC AND GPGGA Sentences
SEND_ALL = "$PMTK314,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0*28\r\n" #Send All Sentences
SEND_NOTHING = "$PMTK314,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0*28\r\n" #Send Nothing
...
That is the GPS Class Mr. McWhorter wrote for a GPS Module in python2. I am trying to configure this python2 source into a workable python3 class.
I am receiving errors like "needs to be bytes" and/or "cannot use bytes here".
Anyway, if you are handy w/ Python3 and know where I am making mistakes on this source to transfer it over to Python3, please let me know. I have tried changing the source many times to accept bytes and to be read as a utf-string.
Here: Best way to convert string to bytes in Python 3? <<< This seems like the most popular topic on this subject but it does not answer my question so far (I think).

Answer 1

This line simply works when adding a b for bytes in front of the string...like so.
(b'$PMTK251,9600*17\r\n')
That should rid you of that error of TypeError: unicode strings are not supported, please encode to bytes: