'Change the node size.
Note: Node must be turned of before changing the size.
:param      node: Node instance
:type       node: :class:`Node`
:param      new_size: NodeSize instance
:type       new_size: :class:`NodeSize`
:return: True on success, False otherwise.
:rtype: ``bool``'

def ex_change_node_size(self, node, new_size):

    if ('instancetype' in node.extra):
        current_instance_type = node.extra['instancetype']
        if (current_instance_type == new_size.id):
            raise ValueError(('New    instance    size    is    the    same    as' + 'the    current    one'))
    attributes = {'InstanceType.Value': new_size.id}
    return self.ex_modify_instance_attribute(node, attributes)
