“…We note that this result has been previously established by Verri [34] in the special setting of purely twisted strips. In fact, in recent years there has been an exponential growth of interest in effective models for thin waveguides under various geometric and analytic deformations, see [12,15,17,29,32,9,8,31,30,35,6,34,7] and further references therein. We refer to [27] for a unifying approach to this type of problems.…”