如何在Perl中调用名称为哈希值的子例程？

$cat test.pl
use Strict;
use warnings;

sub route {
    print "Hello,world!";
}

my %h;
$h{'a'} = 'route';

print "1\n";
$h{a};

print "2\n";
$h{a}();

print "3\n";
"$h{a}".();
$perl test.pl
USELEss use of hash element in void context at test.pl line 12.
USELEss use of concatenation (.) or String in void context at test.pl line 18.
1
2
Can't use String ("route") as a subroutIne ref while "Strict refs" in use at test.pl line 15.
$

调用route()的正确方法是什么？