[abecedarius]

    def is_file_for(is_nagyker, type):
         return (   (type == KIS_ES_NAGYKER)
                 or (type == KISKER and not is_nagyker)
                 or (type == NAGYKER and is_nagyker))

[meowface]

Or maybe

    def is_file_for(is_nagyker, type):
         return (
                    (type == KIS_ES_NAGYKER)
                 or (type == KISKER and not is_nagyker)
                 or (type == NAGYKER and is_nagyker)
                )