public abstract void collectRefs(TObjectIntHashMap<Object> allRefs, TIntHashSet refs);
public abstract void collectVars(TObjectIntHashMap<Variable> allVars, TIntHashSet vars);
public abstract void collectFreeVariables(THashSet<Variable> vars);
public abstract void collectRefs(TObjectIntHashMap<Object> allRefs, TIntHashSet refs);
public abstract void collectVars(TObjectIntHashMap<Variable> allVars, TIntHashSet vars);
public abstract void collectFreeVariables(THashSet<Variable> vars);