'List available sizes containing prices
:rtype: ``list`` of :class:`NodeSize`'

def list_sizes(self):

    result = self.connection.request('/server/type/cloud/').object
    sizes = []
    for value in result.get('data', []):
        value_id = value.get('id')
        size = NodeSize(id=value_id, name=value.get('friendly_name'), ram=value.get('ram'), disk=value.get('storage'), bandwidth=None, price=self._get_size_price(size_id=str(value_id)), driver=self)
        sizes.append(size)
    return sorted(sizes, key=(lambda k: k.price))
