sub use_object_somehow {
      my ($obj, $foo, $bar) = @_;

      carp "Object doesn't quack right" and return
        unless $obj->can("foo") and $obj->can("bar");

      $obj->foo($foo);
      $obj->bar($bar);
    }

##</code><code>##

    sub _check_obj {
      my ($obj, @methods) = @_;

      for (@methods) {
        return unless $obj->can($_);
      }

      return 1;
    }

##</code><code>##

    sub use_object_somehow {
      my ($obj, $foo, $bar) = @_;

      carp "Object doesn't quack right" and return
        unless _check_obj($obj, qw(foo bar));

      $obj->foo($foo);
      $obj->bar($bar);
    }