private static MethodCallExpression CountDistinctExpression(ParameterExpression sourceParameter, LambdaExpression lambda)
{
MethodInfo selectMetodInfo = OeMethodInfoHelper.GetSelectMethodInfo(lambda.Parameters[0].Type, lambda.ReturnType);
MethodCallExpression selectCall = Expression.Call(selectMetodInfo, sourceParameter, lambda);
MethodInfo distinctMethodInfo = OeMethodInfoHelper.GetDistinctMethodInfo(lambda.ReturnType);
MethodCallExpression distinctCall = Expression.Call(distinctMethodInfo, selectCall);
MethodInfo countMethodInfo = OeMethodInfoHelper.GetCountMethodInfo(lambda.ReturnType);
return(Expression.Call(countMethodInfo, distinctCall));
}