user_histories = {
    1: {'fiction': 5, 'non_fiction': 2, 'science': 0, 'fantasy': 0},
    2: {'fiction': 1, 'non_fiction': 4, 'science': 1, 'fantasy': 2},
    3: {'fiction': 0, 'non_fiction': 1, 'science': 5, 'fantasy': 0},
    4: {'fiction': 1, 'non_fiction': 0, 'science': 0, 'fantasy': 6},
}


def get_user_history(user_id: int) -> dict:
    """
    Retorna o histórico de compras do usuário.
    """
    return user_histories.get(user_id)