u of a list, a single class can be used as the `classFilterList` parameter.

>>> a = stream.Stream()
>>> a.repeatInsert(note.Rest(), list(range(10)))
>>> for x in range(4):
...     n = note.Note('G#')
...     n.offset = x * 3
...     a.insert(n)
>>> found = a.getElementsNotOfClass(note.Note)
>>> len(found)
10

>>> b = stream.Stream()
>>> b.repeatInsert(note.Rest(), list(range(15)))
>>> a.insert(b)

Here, it gets elements from within a stream
this probably should not do this, as it is one layer lower

>>> found = a.flatten().getElementsNotOfClass(note.Rest)
>>> len(found)
4
>>> found = a.flatten().getElementsNotOfClass(note.Note)
>>> len(found)
25
Fİ