Expand shelf ranges

Shelf labels are given as a string like "3-5, 8, 10-11": comma-separated, each part either a single number or a range a-b inclusive. Write expand(text) that returns the full list of numbers in order.

expand("3-5, 8, 10-11")  ->  [3, 4, 5, 8, 10, 11]
expand("7")              ->  [7]

def expand(text):
    ...