Pygame Combo Example.

import pygame

key_code = pygame.key.key_code

class Scene:
    def __init__(self, control):
        self.control = control

    def on_draw(self, surface): pass
    def on_event(self, event): pass
    def on_update(self, delta): pass

class SceneHandler:
    def __init__(self):
        self._current = None
        self._next = None

    def set(self, scene):
        if self._current:
            self._next = scene
        else:
            self._current = scene

    def update(self):
        if self._next:
            self._current = self._next
            self._next = None

        return self._current

class SceneControl:
    def __init__(self, caption, size, flags=0, fps=60):
        pygame.display.set_caption(caption)
        self.display = pygame.display.set_mode(size, flags)
        self.rect = self.display.get_rect()
        self.clock = pygame.time.Clock()
        self.handler = SceneHandler()
        self.running = True
        self.delta = 0
        self.fps = fps

    def run(self, scene):
        self.handler.set(scene)
        while self.running:
            scene = self.handler.update()
            for event in pygame.event.get():
                if event.type != pygame.QUIT:
                    scene.on_event(event)
                else:
                    self.running = False

            scene.on_update(self.delta)
            scene.on_draw(self.display)
            pygame.display.flip()
            self.delta = self.clock.tick(self.fps)

class Timer:
    def __init__(self, interval):
        self.interval = interval
        self.timer = 0

    def action(self, ticks):
        return 0 < self.timer > ticks

    def clear(self):
        self.timer = 0

    def set(self):
        self.timer = pygame.time.get_ticks() + self.interval

class AttackState:
    def __init__(self, combos, interval):
        self.combos = combos
        self.timer = Timer(interval)
        self.state = None

    def action(self, key):
        if self.state:
            if key in self.combos[self.state]:
                ticks = pygame.time.get_ticks()
                if self.timer.action(ticks):
                    print(self.combos[self.state][key])
                else:
                    print("Time Elapse")
                    self.update(key)
            else:
                self.update(key)
        else:
            self.update(key)

    def update(self, key):
        if key in self.combos:
            self.state = key
            self.timer.set()
        else:
            self.state = None
            self.timer.clear()

class Player:
    def __init__(self, combos):
        self.state = AttackState(combos, 500)

    def attack(self, event):
        self.state.action(event.key)
        print(self.state.state)

class ComboExample(Scene):
    def __init__(self, control):
        super().__init__(control)
        self.background = 'black'
        self.player = Player(self.combo_set_a())

    def combo_set_a(self):
        return {
            key_code('j'): {key_code('u'): 'Combo 1'},
            key_code('k'): {key_code('i'): 'Combo 2'}
        }

    def on_draw(self, surface):
        surface.fill(self.background)

    def on_event(self, event):
        if event.type == pygame.KEYDOWN:
            self.player.attack(event)

pygame.init()
control = SceneControl("Combo Example", (600, 600))
control.run(ComboExample(control))
pygame.quit()