P:=PSL(3,4);
A:=TrivialGModuleAsGOuterGroup(P,CyclicGroup(4));
R:=ResolutionFiniteGroup(P,3);
C:=HomToGModule(R,A);
CH:=CohomologyModule(C,2);
classes:=Elements(ActedGroup(CH));
c:=CH!.representativeCocycle(classes[2]);
f:=Mapping(c);
Agroupe:=ActedGroup(A);
extension := CcGroup(A,c);
Read("BogomolovModP.g");
BogomolovMultiplierModP(extension,2);