GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
Read( "Coupling.g" ); II_E := GrothendieckSpectralSequence( RightDualizingFunctor( A3 ), LeftDualizingFunctor( A3 ), N ); filt := FiltrationBySpectralSequence( II_E ); m := IsomorphismOfFiltration( filt );