package Foo;
@EXPORT_OK = qw(get_foo);

sub new {
    # constructer
}

sub get {
    # for OO interface
}

sub get_foo {
    # for procedural interface
}

1;

##</code><code>##

$o = Foo->new();
$o->get($key);     # of cource, $value
$o->get_foo($key); # what's this?