feels good my solution is the same as the fist ranking solution

The other good option is Ellipsis.

It worked fine when I ran the code. Are you sure you're not mistaken? Does the test give a list with [None] and is it a requirement?

Does not work when None is present, f.e. the list [None] as input won't work.

i like this one

First time have identical solution. I'm surprised best solution isn't oneliner (-:

I like it because it's not a one-liner haha

great minds think alike >.<

For prev, It's better to use float('NaN') instead of None.

float('NaN') shouldn't be equal to any object.

Interesting idea! Probably should be more efficient)

This is what I had in mind. But I just couldn't translate into code. Fumbled over this one for quite a while.

coppied? XD

Very similar to mine. I should have named the result "result" not "output"