push

what is the output of this script, could you explain?

hint:

push, ‘,’ operator and the precedence

use v5.20;
my @b = (1..5);
my @a = (1..5);

be carefull about the ‘,’ after 6

push @a, 6,
push @b, 7;
say join('-', @a);
say join('-', @b);
h