def triangle_shape_corr(n, fillchar="x", spacechar=" "):
    """Return a string made of ``fillchar`` and ``spacechar``representing a triangle shape of height ``n``.

    For n=0, return ``""``.

    .. testcode::

        from lab1.functions import triangle_shape
        print(triangle_shape(6, fillchar="x", spacechar="_"))

    .. testoutput::

        _____x_____
        ____xxx____
        ___xxxxx___
        __xxxxxxx__
        _xxxxxxxxx_
        xxxxxxxxxxx

    Args:
        n (int): height of the triangle.
        fillchar (str, optional): Defaults to "x".
        spacechar (str, optional): Defaults to " ".

    Returns:
        str: string representation of the triangle.
    """
    width = 2 * n - 1
    return "\n".join(
        (fillchar * (2 * i + 1)).center(width, spacechar) for i in range(n)
    )