Pyserial for Arduino - Python end

# should send 'foobar~' to the arduino over serial. The corresponding arduino code will echo all the characters back, # this program will then reconstitute them as characters, then stop listening and print the joined result on
# receiving '#'

import serial
import io
from time import sleep

ser = serial.Serial("/dev/ttyACM0", 9600, timeout=1)
sleep(2)
print ser.portstr
ser.write("foobar~")
value = None
rawVal = ''
chrValue = ''
received = ''
esc = False
while esc == False:
    rawVal = ser.readline()
    print "raw data received: ", rawVal
    try:
        value = int(float(rawVal))
        chrValue = chr(value)
    except ValueError:
        chrValue = rawVal
    received = received + chrValue
    valBuf = chrValue.rstrip('\n')
    valBuf = valBuf.rstrip('\r')
    valBuf = valBuf.rstrip(' ')
    if valBuf == '~':
        print "escape character detected"
        esc = True
print "joined data: ", received
ser.close()