def listSymmetricDifference(x, y):
    """
    Symmetric Difference of two lists.

    Parameters
    ----------
    x, y: list of any
        The two list of which we want the symmetric difference.

    Returns
    -------
    list of any
        The list of elements that appear exactly once in either x or y.
    """
    return list(set(x) ^ set(y))