These bugs will not be fixed in the short term:

IsFiniteState	never detects loops or patterns in the states, if not f.s.

Iterator	not coded for FullSCxxx(IsBounded,IsFiniteState,...)

PeriodicList	no method for Concatenation and Apply

IsTorsion	is not proven to give the right answer

\in		for groups without the congruence property, it's hard to find good quotients. E.g.,
	gap> AssignGeneratorVariables(GrigorchukTwistedTwin);
	gap> epi := EpimorphismGermGroup(GrigorchukTwistedTwin,4);;
	gap> s := Group(Comm(a,x),Comm(a,y),Comm(x,z),Comm(y,z));;
	gap> Image(epi,Comm(a,x)^z) in Image(epi,s);
	true
