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Deep flatten list

Deep flattens a list.

Use recursion.
Use isinstance() with collections.abc.Iterable to check if an element is iterable.
If it is iterable, apply deep_flatten() recursively, otherwise return [lst].

from collections.abc import Iterable

def deep_flatten(lst):
  return ([a for i in lst for a in
          deep_flatten(i)] if isinstance(lst, Iterable) else [lst])

deep_flatten([1, [2], [[3], 4], 5]) # [1, 2, 3, 4, 5]

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