Panda3D key hold

from direct.showbase.ShowBase import ShowBase
from direct.task import Task

class Game(ShowBase):

    def __init__(self):
        super().__init__()

        self.keys = {
            "a": False,
        }

        self.accept("a", self.key_down, ["a"])
        self.accept("a-up", self.key_up, ["a"])

        taskMgr.add(self.check_key_state, "check_key_state")

    def key_down(self, key):
        self.keys[key] = True

    def key_up(self, key):
        self.keys[key] = False

    def check_key_state(self, task):
        if self.keys["a"]:
            print("Key 'a' is held down")
        else:
            print("Key 'a' is not held down")
        return Task.cont

game = Game()
game.run()