Thanks for taking the time to explain. I'm finding this a really good way to learn new functions and your example spawned a VERY late night of reading on sort() and lambda.
Very much appreciated.

yes. much clearer. thanks. :-)

See if it's clearer now.

I just meant that it's not a very clear way of saying it.
If anyone can update the instructions, it would be clearer to say

"You always walk only a single block for each letter".

to me, "You always walk only a single block in a direction" implies that there needs to be a test for sets of instructions containing n{2,} etc.

It means you always go one block for direction (or letter).

The instructions say "You always walk only a single block in a direction" but some of the test cases contain n,n|s,s|e,e|w,w instructions.
Surely that is the same as two blocks in any direction?