my ($blah) = @_;   # note the ()s. w/o them $blah is the size of @_.
my  $blah  = shift;

##</code><code>##

my ($first, $second, @rest) = @_;

##</code><code>##

sub frontend { shift->backend("an extra arg", @_) }

##</code><code>##

sub mine ($blah) {
    say "$blah is now visible here.";
}