code: def get_group_by_id(self, group_id: str) -> typing.Optional['Group']:
          
          VALID_POSITIVE_INT.validate(group_id, 'get_group_by_id', exc=ValueError)
          for group in self.groups:
  
              if group.group_id == group_id:
                  return group
          return None
docs: Gets a group by id
  
          Args:
              group_id: group id
  
          Returns: Group