“…Here the waveguide was three-dimensional and the nontrivial geometry came from localized twisting which was scaled together with the width as the bending in [1], [14], [15], [16]. The operator in [1], [14], [16], [29] was the Dirichlet Laplacian, while in [15] it was the Robin Laplacian. The main result of [1], [14], [15], [16], [29] is the convergence theorems.…”