Wave Test

import threading
from time import sleep
from random import randint
import string

class Bouncer (threading.Thread):
    def __init__ (self):
        threading.Thread.__init__ (self)
        self.max = 59 #Max width of the screen
        self.sleeptime = 50 #MS delay. Sets wave speed
        self.sleeplock = threading.Lock ()
        self.chars = string.ascii_letters + string.digits + string.punctuation

    def rand_char (self):
        return self.chars [randint (0, len (self.chars) - 1)]

    def set_rate (self, nvalue):
        with self.sleeplock:
            try:
                nvalue = int (nvalue)
                self.sleeptime = nvalue
            except ValueError as e:
                self.sleeptime = 2000
                print ("Incorrect input type:", e)

    def wave (self):
        pad = 0
        dir = 'r'
        padchar = ' '
        while True:
            if dir == 'l':
                pad += -1
            elif dir =='r':
                pad += 1

            if randint (0, 1000) == 0:
                padchar = '!'

            yield (padchar * pad)

            if pad > self.max:
                dir = 'l'
            elif pad < 0:
                dir = 'r'
            padchar = ' '

    def run (self):
        for p in self.wave ():
            print (p + self.rand_char ())
            with self.sleeplock:
                sleep (self.sleeptime / 1000)

wave = Bouncer ()
wave.start ()

while True:
    wave.set_rate (input (""))