@classmethod
def clean_unusable_keys(cls, resource):
    """Delete keys of dictionary not used

        :param resource: dictionary got from alignak-backend
        :type resource: dict
        :return:
        """
    fields = ['_links', '_updated', '_created', '_etag', '_id', 'name',
        'ui', '_realm', '_sub_realm', '_users_read', '_users_update',
        '_users_delete', '_parent', '_tree_parents', '_all_children',
        '_level', 'customs', 'host', 'service', 'back_role_super_admin',
        'token', '_templates', '_template_fields', 'note', '_is_template',
        '_templates_with_services', '_templates_from_host_template',
        'merge_host_users', 'hosts_critical_threshold',
        'hosts_warning_threshold', 'services_critical_threshold',
        'services_warning_threshold', 'global_critical_threshold',
        'global_warning_threshold', '_children', 'hostgroups', 'hosts',
        'dependent_hostgroups', 'dependent_hosts', 'servicegroups',
        'services', 'dependent_servicegroups', 'dependent_services',
        'usergroups', 'users', 'location', 'duplicate_foreach', 'tags',
        '_overall_state_id', 'trigger', 'schema_version']
    for field in resource:
        if field.startswith('ls_'):
            fields.append(field)
    for field in fields:
        if field in resource:
            del resource[field]
