(def avg2 (lst) (avg (flat lst)))
'(1 2 3 (3 4 5) (3 4 (1 2 3)))
(/ (+ 1 2 3 (/ (+ 3 4 5) 3) (/ (+ 3 4 (/ (+ 1 2 3) 3)) 3)) 5) ;= 13/5
(/ (+ 1 2 3 3 4 5 3 4 1 2 3) 11) ;= 31/11
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