## flatten_list()


Flatten an arbitrarily nested list into a single flat list.


Usage


``` python
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

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

\[1, 2, 3, 4, 5, 6\]

``` python
>>> flatten_list([[["deep"]]])
```

\['deep'\]