The rumor was that the standard extension methods on IEnumerable<T> like Join, Select, Where, Group were all implemented on top of SelectMany. I call it a rumo

The rumor was that the standard extension methods on IEnumerable<T> like Join, Select, Where, Group were all implemented on top of SelectMany. I call it a rumor because I cannot remember where I read it, so it is quite possible I have misunderstood it.