'Creates a shared IP group.
:param       group_name:  group name which should be used
:type        group_name: ``str``
:param       node_id: ID of the node which should be used
:type        node_id: ``str``
:rtype: ``bool``'

def ex_create_ip_group(self, group_name, node_id=None):

    if isinstance(node_id, Node):
        node_id = node_id.id
    group_elm = ET.Element('sharedIpGroup', {'xmlns': self.XML_NAMESPACE, 'name': group_name})
    if node_id:
        ET.SubElement(group_elm, 'server', {'id': node_id})
    resp = self.connection.request('/shared_ip_groups', method='POST', data=ET.tostring(group_elm))
    return self._to_shared_ip_group(resp.object)
