$ perl -Mstrict -Mwarnings -e '
my $x;
my $x;
'
"my" variable $x masks earlier declaration in same scope at -e line 3.

##</code><code>##

$ perl -Mstrict -Mwarnings -E '
my @numbers = (2, 1, 3);
my @strings = qw{B A C};
say sort { $a <=> $b } @numbers;
say sort { $b <=> $a } @numbers;
say sort { $a cmp $b } @strings;
say sort { $b cmp $a } @strings;
'
123
321
ABC
CBA