>>> from so2_levels import average

>>> m = average([10.5, 9.7, 11.2])
>>> round(m, 4)
10.4667
>>> m = average([12, 11, 13, 12])
>>> round(m, 3)
12.0
>>> m = average([10.5, -1, 9.7, 11.2, -2.5])
>>> round(m, 4)
10.4667
>>> m = average([13])
>>> round(m, 3)
13.0