How to use the meshplex.exceptions.MeshplexError function in meshplex

#     expression
    #
    #         ce0 =  * 0.5 / sqrt(alpha)
    #
    #     with
    #
    #         alpha =  * 
    #               +  * 
    #               +  * .
    #
    # Note that some simplifications are achieved by virtue of
    #
    #   e1 + e2 + e3 = 0.
    #
    if not numpy.all(tri_areas > 0.0):
        raise MeshplexError("Degenerate cell.")

    return -ei_dot_ej * 0.25 / tri_areas[None]