keys check with set

from tkinter import *
from random import randrange as rnd

root = Tk()
root.geometry('600x600')

canv = Canvas(bg='white')
canv.pack(fill=BOTH,expand=1)


keys = set()

def check():
    #print(keys)
    if 37 in keys:
        print('left')
    if 39 in keys:
        print('right')
    root.after(30,check)

def keyDown(event):
    keys.add(event.keycode)

def keyUp(event):
    keys.remove(event.keycode)

root.bind('<Key>',keyDown)
root.bind('<KeyRelease>',keyUp)
check()

root.mainloop()