I always see the question in C# forum on what is the use of IEnumerable and how to return var. These 2 questions are somehow related. One of the uses of IEnumerable is to return var in a function, see the sample below.
// QueryMethhod1 returns a query as its value.
publicstaticIEnumerable<string> QueryMethod1(refint ints)
var intsToStrings = from i in ints
where i > 4
For other detail see the resources below.