overwright lines

import sys

textlen = 0 #used to clear lines this is required or with input of "hello" and "test" it will show "testo"
def writeline(text):
    global textlen
    if text== "" or not isinstance(text, basestring):
        raise "Requred string is not set" ##basic error handeling (this may be incorrect, im using classes where i got this code from
    sys.stdout.write('\r' + ' ' * textlen + '\r') ##pints spaces equle to the amount of characters from the last message and overwrights the last message
    sys.stdout.flush()
    sys.stdout.write('\r' + str(text) + '\r') ##overwrights those spaces with new characters
    sys.stdout.flush()
    textlen = len(text)