i've been struggling with python incomprehensions since time immemorial. map/filter are a breeze.

It's easy. The first bit:

    [person

tells you that you're getting a list of persons. That's the most important part. The rest is telling you how they're getting in that list.

It's almost like a select query in (pseudo) SQL.

    select person from people where person.isvalid = true

vs

    [person for person in people if person.isvalid]