I thought this would be straightforward but after a lot of searching I cannot find the answer. I want to return the next item in a list.

So, in the example below I want to return `l4.pkl`.

```
list_numbers = ['l1.pkl', 'l2.pkl', 'l3.pkl', 'l4.pkl', 'l5.pkl', 'l6.pkl']
element = 'l3.pkl'

```