l = [[[1], [2], [3], [4], [5]], [[6], [7], [8], [None], [None]], [[11], [12
    ], [None], [None], [None]]]
l = [[x[0] for x in s if x[0] is not None] for s in l]
How can I remove the inner most level of nesting on a list of lists of varying lengths?