GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
# Line with C2-iso and a V4-point M := [ [1,2] ]; C2 := Group( (1,2) ); V4 := Group( (1,2), (3,4) ); iso := rec( 2 := V4, 1 := C2 ); mu := []; dim := 5; #------------------------------------------>>>> Z^(1 x 1) #------------------------------------------>>>> 0 #------------------------------------------>>>> Z/< 2 > + Z/< 2 > #------------------------------------------>>>> Z/< 2 > #------------------------------------------>>>> Z/< 2 > + Z/< 2 > + Z/< 2 > #------------------------------------------>>>> Z/< 2 > + Z/< 2 > #------------------------------------------>>>> Z/< 2 > + Z/< 2 > + Z/< 2 > + Z/< 2 > #