internal protected override Expression ToExpression(OverloadResolver resolver, IList<Expression> parameters, bool[] hasBeenUsed) {
Debug.Assert(hasBeenUsed.Length == parameters.Count);
Debug.Assert(_index < parameters.Count);
Debug.Assert(parameters[_index] != null);
Debug.Assert(!hasBeenUsed[Index]);
hasBeenUsed[_index] = true;
return resolver.ConvertExpression(parameters[_index], ParameterInfo, _parameterType);
}
