flatten_list()

Flatten an arbitrarily nested list into a single flat list.

Usage

flatten_list(nested)

Recursively traverses the input list and collects all non-list elements into a single flat list.

Parameters

nested: list

A potentially nested list of values.

Returns

list

A flat list containing all leaf elements.

Notes

The function uses recursion to handle arbitrarily deep nesting. For each element in the input, it checks whether the element is itself a list. If so, it recurses into that sublist. Otherwise, the element is appended to the result.

Because Python has a default recursion limit of 1000, this function will raise a RecursionError for lists nested deeper than approximately 500 levels (accounting for the two-frame overhead per recursive call).

The implementation allocates a new list and extends it with each recursive result. The overall time complexity is O(n) where n is the total number of leaf elements, but the constant factor depends on the nesting depth due to intermediate list allocations.

Examples

>>> flatten_list([1, [2, [3, 4], 5], 6])
[1, 2, 3, 4, 5, 6]

>>> flatten_list([[["deep"]]])
['deep']