Returns an input/output node tensor where the second basis is merely the prime of the first basis.
References syten::STensorImpl::SBasis::f(), gen_io(), and syten::STensorImpl::SBasis::prime().
Referenced by syten::IPEPSv2::Lattice::get(), syten::T3N::VarationalTrunc::init_contr_rec(), syten::MPS::overlap(), and syten::T3N::VarationalTrunc::VarationalTrunc().