Python-сообщество

 [[[[]]]], [], 5] => [5]

 def del_null(x):
	for p in x:
		if isinstance(p, list) and len(p) != 0:
			del_null(p)
		elif isinstance(p, list):
			del p

  
>>> def f(lst):
...     out = []
...     for i in lst:
...         if isinstance(i, list):
...             if i:
...                o = f(i)
...                if o:
...                    out.append(o)
...         else:
...             out.append(i)
...     return out
... 
>>> f([[[[[]]]], [], 5])
[5]
>>> f([])
[]
>>> f([[]])
[]
>>> f([[], 1])
[1]
>>> f([[], [[1], []]])
[[[1]]]
>>>