Help ....Coding Explaination for to find most frequent number

Question

My questions is what is happening in this code (how the code run) and why count function written as "x.count" instead "x.count()" and and can i replace key with another variable. I really lost😭😭🥺
https://code.sololearn.com/cJzG5LA8qPbS/?ref=app

Answer 1

1. You create a Set to get rid of double numbers.
The key argument of the max-function expects a function, not a function-call.