return ans;
}
/** Returns the AlloyType corresponding to the given sig; create an AlloyType for it if none existed before. */
private AlloyType sigMETA(PrimSig s) throws Err {
if (s==Sig.NONE) throw new ErrorFatal("Unexpected sig \"none\" encountered.");
AlloyType type = sig2type.get(s);
if (type != null) return type;
if (s==Sig.UNIV) type=AlloyType.UNIV;
else if (s==Sig.SIGINT) type=AlloyType.INT;
else if (s==Sig.SEQIDX) type=AlloyType.SEQINT;