return addOrCheckDefinition(valueVarName, value, bindingSet);
bindingSet = addOrCheckDefinition(valueVarName, value, bindingSet); if (bindingSet == null) return null; return new MatchResult(this, bindingSet);
	protected BindingSet checkConsistent(Variable field, Variable value, BindingSet bindingSet) {		// Ensure that the field and value variables are consistent with		// previous definitions (if any)		bindingSet = addOrCheckDefinition(fieldVarName, field, bindingSet);		if (bindingSet == null)			return null;		return addOrCheckDefinition(valueVarName, value, bindingSet);	}