if (DEBUG) System.out.println("\tConflicting variable " + varName);
if (DEBUG) System.out.println("\tConflicting variable " + varName + ": " + variable + " != " + existingVariable);
	protected static BindingSet addOrCheckDefinition(String varName, Variable variable, BindingSet bindingSet) {		Variable existingVariable = lookup(varName, bindingSet);		if (existingVariable == null) {			bindingSet = new BindingSet(new Binding(varName, variable), bindingSet);		} else {			if (!existingVariable.sameAs(variable)) {				if (DEBUG) System.out.println("\tConflicting variable " + varName);				return null;			}		}		return bindingSet;	}