def add_groups_to_user(id, group_list = [])
      wf_user_id?(id)
      validate_usergroup_list(group_list)
      api.post([id, 'addUserGroups'].uri_concat, group_list,
               'application/json')
    end
def add_groups_to_user(id, group_list = [])
      wf_user_id?(id)
      validate_usergroup_list(group_list)
      api.post([id, 'addUserGroups'].uri_concat, group_list,
               'application/json')
    end
POST /api/v2/user/{id}/addUserGroups
 Adds specific user groups to the user

 @param id [String] ID of the user
 @param group_list [Array[String]] list of groups to add
 @return [Wavefront::Response]