Flattening a list recursively [duplicate]

Answer 1

Here's a possible solution without any loops or list comprehensions, just using recursion:

def flatten(test_list):
    if isinstance(test_list, list):
        if len(test_list) == 0:
            return []
        first, rest = test_list[0], test_list[1:]
        return flatten(first) + flatten(rest)
    else:
        return [test_list]