code: def add_member(self, contact_name, contactgroup_name):
          
          contactgroup = self.find_by_name(contactgroup_name)
          if not contactgroup:
              contactgroup = Contactgroup({'contactgroup_name': contactgroup_name,
                                           'alias': contactgroup_name,
                                           'members': contact_name})
              self.add_contactgroup(contactgroup)
          else:
              contactgroup.add_members(contact_name)
docs: Add a contact string to a contact member
          if the contact group do not exist, create it
  
          :param contact_name: contact name
          :type contact_name: str
          :param contactgroup_name: contact group name
          :type contactgroup_name: str
          :return: None