Update player_functions.py

        try:

            retry=1

            while retry==1:

                time.sleep(.5)

                if(proc.poll() is not None):

                    retry=0

                    received_char=""

                    while received_char is not "E":

                        # Read one byte from the serial port

                        data = display.read()

                        # Decode the byte to a string

                        received_char = data.decode('utf-8')

                        # Check if the received character is 'E'

                        if received_char == 'E':

                            print("Received 'E' from serial port.")

        finally:

            # When we've stopped retrying, either because of stop command

            # or a finished track, terminate the subprocess if it hasn't already been