has 'node' => ( is => 'rw', isa => 'Any' );
Moose generates a read-write accessor for this attribute. The type
-constraint is C<Any>, which means literally means it can contain
-anything.
+constraint is C<Any>, which literally means it can contain anything.
We could have left out the C<isa> option, but in this case, we are
including it for the benefit of other programmers, not the computer.