How do I Aggregate multiple IEnumerables of T

Question

Given....

Public MasterList as IEnumerable(Of MasterItem)
Public Class MasterItem(Of T) 
    Public SubItems as IEnumerable(Of T)
End Class 

I

Answer 1

I know in C# there is the yield operator for loops. Just iterate and yield return each sub item recursively. Apparently, there is no yield for VB, sorry.