removed self from is_transboundary method as it's obvious that it's an instance method
removed self from is_transboundary method as it's obvious that it's an instance method

unepwcmc/ProtectedPlanet,unepwcmc/ProtectedPlanet,unepwcmc/ProtectedPlanet,unepwcmc/ProtectedPlanet,unepwcmc/ProtectedPlanet