nontype error obj has no attribute shoot

hello, i have a huge problem and dont know how to fix it. here is the code:

#(in class)
def shoot(self, current_time, bullet_group, enemy_group):
    if current_time - self.last_shot > self.shoot_count:
        bullet = Bullet(self.rect.centerx, self.rect.bottom, "death_star_laser1.png", 10)
        bullet_group.add(bullet)
        if current_time - self.last_shot > self.cooldown:
            self.last_shot = current_time
            return random.choice(enemy_group.sprites())     

#(just normal written in file)
if len(speed_enemy_group) > 0:
    choose_boss= random.choice(boss_enemy_group.sprites())

#(in while loop)
   if len(speed_enemy_group) > 0:
            choose_boss= choose_boss.shoot(time_now, enemy_bullet_group, boss_enemy_group)

i get error nontype ...

its because choose_boss(time_now,... --> choose_boss is yellow. but when i put the definition of choose boss in my while loop all is great but i wont do that because boss is shootng multiple bullets in one row and if i put "choose_boss= random.choice(speed_enemy_group.sprites())" in the while loop every time its another boss who shooting..

im happy if somebody can look at ths