$ > xxx 2> yyy
$ perl -Mstrict -Mwarnings -E '
    sub same_mod_time { (stat($_[0]))[9] == (stat($_[1]))[9] }
    say ">>>" . same_mod_time(qw{xxx yyy}) . "<<<";
'
>>>1<<<
$ perl -Mstrict -Mwarnings -E '
    sub same_mod_time { (stat($_[0]))[9] == (stat($_[1]))[9] }
    say 0 + same_mod_time(qw{xxx yyy});
'
1
$ > xxx
$ perl -Mstrict -Mwarnings -E '
    sub same_mod_time { (stat($_[0]))[9] == (stat($_[1]))[9] }
    say ">>>" . same_mod_time(qw{xxx yyy}) . "<<<";
'
>>><<<
$ perl -Mstrict -Mwarnings -E '
    sub same_mod_time { (stat($_[0]))[9] == (stat($_[1]))[9] }
    say 0 + same_mod_time(qw{xxx yyy});
'
0