'Search for a group where to create the node.
If we can not find any group, create it into argument \'location\''

def _define_create_node_group(self, xml_loc, loc, **kwargs):

    if ('group_name' not in kwargs):
        group_name = NodeGroup.DEFAULT_GROUP_NAME
    else:
        group_name = kwargs['group_name']
    groups_link = get_href(xml_loc, 'virtualappliances')
    groups_hdr = {'Accept': self.VAPPS_MIME_TYPE}
    vapps_element = self.connection.request(groups_link, headers=groups_hdr).object
    target_group = None
    for vapp in vapps_element.findall('virtualAppliance'):
        if (vapp.findtext('name') == group_name):
            uri_vapp = get_href(vapp, 'edit')
            return NodeGroup(self, vapp.findtext('name'), uri=uri_vapp)
    if (target_group is None):
        return self.ex_create_group(group_name, loc)
