def soma(x, y):
    """Soma x e y

    >>> soma(10, 20)
    30

    >>> soma(-10, 20)
    10

    >>> soma('10', 20)
    Traceback (most recent call last):
    ...
    AssertionError: x precisa ser int ou float
    """
    assert isinstance(x, (int, float)), "x precisa ser int ou float"
    assert isinstance(y, (int, float)), "y precisa ser int ou float"
    return x + y


def subtrai(x, y):
    """Subtrai x e y

    >>> subtrai(10, 5)
    5

    >>> subtrai('10', 5)
    Traceback (most recent call last):
    ...
    AssertionError: x precisa ser int ou float
    """
    assert isinstance(x, (int, float)), "x precisa ser int ou float"
    assert isinstance(y, (int, float)), "y precisa ser int ou float"
    return x - y


if __name__ == "__main__":
    import doctest

    doctest.testmod(verbose=True)
