How to use the splipy.Surface.make_splines_identical function in Splipy

# create linear interpolation between opposing sides
    s1 = edge_curves(bottom, top)
    s2 = edge_curves(left, right)
    s2.swap()
    # create (linear,linear) corner parametrization
    linear = BSplineBasis(2)
    rat = s1.rational  # using control-points from top/bottom, so need to know if these are rational
    if rat:
        bottom = bottom.clone().force_rational() # don't mess with the input curve, make clone
        top.force_rational()                     # this is already a clone
    s3 = Surface(linear, linear, [bottom[0], bottom[-1], top[0], top[-1]], rat)

    # in order to add spline surfaces, they need identical parametrization
    Surface.make_splines_identical(s1, s2)
    Surface.make_splines_identical(s1, s3)
    Surface.make_splines_identical(s2, s3)

    result = s1
    result.controlpoints += s2.controlpoints
    result.controlpoints -= s3.controlpoints
    return result

else:
        x = [s.center() for s in surfaces]

        # create knot vector from the euclidian length between the surfaces
        dist = [0]
        for (x1,x0) in zip(x[1:],x[:-1]):
            dist.append(dist[-1] + np.linalg.norm(x1-x0))

        # using "free" boundary condition by setting N'''(u) continuous at second to last and second knot
        knot = [dist[0]]*4 + dist[2:-2] + [dist[-1]]*4
        basis3 = BSplineBasis(4, knot)

    n = len(surfaces)
    for i in range(n):
        for j in range(i+1,n):
            Surface.make_splines_identical(surfaces[i], surfaces[j])

    basis1 = surfaces[0].bases[0]
    basis2 = surfaces[0].bases[1]
    m1     = basis1.num_functions()
    m2     = basis2.num_functions()
    dim    = len(surfaces[0][0])
    u      = basis1.greville() # parametric interpolation points
    v      = basis2.greville()
    w      = dist

    # compute matrices
    Nu     = basis1(u)
    Nv     = basis2(v)
    Nw     = basis3(w)
    Nu_inv = np.linalg.inv(Nu)
    Nv_inv = np.linalg.inv(Nv)

# create linear interpolation between opposing sides
    s1 = edge_curves(bottom, top)
    s2 = edge_curves(left, right)
    s2.swap()
    # create (linear,linear) corner parametrization
    linear = BSplineBasis(2)
    rat = s1.rational  # using control-points from top/bottom, so need to know if these are rational
    if rat:
        bottom = bottom.clone().force_rational() # don't mess with the input curve, make clone
        top.force_rational()                     # this is already a clone
    s3 = Surface(linear, linear, [bottom[0], bottom[-1], top[0], top[-1]], rat)

    # in order to add spline surfaces, they need identical parametrization
    Surface.make_splines_identical(s1, s2)
    Surface.make_splines_identical(s1, s3)
    Surface.make_splines_identical(s2, s3)

    result = s1
    result.controlpoints += s2.controlpoints
    result.controlpoints -= s3.controlpoints
    return result

In case of six input surfaces, these must be given in the order: bottom,
    top, left, right, back, front. Opposing sides must be parametrized in the
    same directions.

    :param [Surface] surfaces: Two or six edge surfaces
    :return: The enclosed volume
    :rtype: Volume
    :raises ValueError: If the length of *surfaces* is not two or six
    """
    if len(surfaces) == 1: # probably gives input as a list-like single variable
        surfaces = surfaces[0]
    if len(surfaces) == 2:
        surf1 = surfaces[0].clone()
        surf2 = surfaces[1].clone()
        Surface.make_splines_identical(surf1, surf2)
        (n1, n2, d) = surf1.controlpoints.shape  # d = dimension + rational

        controlpoints = np.zeros((n1, n2, 2, d))
        controlpoints[:, :, 0, :] = surf1.controlpoints
        controlpoints[:, :, 1, :] = surf2.controlpoints

        # Volume constructor orders control points in a different way, so we
        # create it from scratch here
        result = Volume(surf1.bases[0], surf1.bases[1], BSplineBasis(2), controlpoints,
                         rational=surf1.rational, raw=True)

        return result
    elif len(surfaces) == 6:
        if any([surf.rational for surf in surfaces]):
            raise RuntimeError('edge_surfaces not supported for rational splines')

left.reverse()

    # create linear interpolation between opposing sides
    s1 = edge_curves(bottom, top)
    s2 = edge_curves(left, right)
    s2.swap()
    # create (linear,linear) corner parametrization
    linear = BSplineBasis(2)
    rat = s1.rational  # using control-points from top/bottom, so need to know if these are rational
    if rat:
        bottom = bottom.clone().force_rational() # don't mess with the input curve, make clone
        top.force_rational()                     # this is already a clone
    s3 = Surface(linear, linear, [bottom[0], bottom[-1], top[0], top[-1]], rat)

    # in order to add spline surfaces, they need identical parametrization
    Surface.make_splines_identical(s1, s2)
    Surface.make_splines_identical(s1, s3)
    Surface.make_splines_identical(s2, s3)

    result = s1
    result.controlpoints += s2.controlpoints
    result.controlpoints -= s3.controlpoints
    return result