GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
LoadPackage( "MatricesForHomalg" ); R := HomalgRingOfIntegers( ); m := HomalgMatrix( "[ \ 2, 0, 0, \ 0, 12, 0 \ ]", 2, 3, R ); LoadPackage( "Modules" ); M := LeftPresentation( m ); N := TorsionObject( M );