Difference between interface as type constraint and interface as parameter?

Question

If I wanted to create a method that takes an instance of IList as a parameter (or any other interface, but let\'s use IList as an example), I could cre

Answer 1

if Foo2 returns void, it doesn't really matter. But suppose Foo2 returned a modified version of the list. With an IList parameter, the best it could do is return another IList. But with an IList constraint, it could return any type the caller wants assuming that type implements IList