code: def get_group_by_name(self, group_name: str) -> typing.Optional['Group']:
          
          VALID_STR.validate(group_name, 'get_group_by_name')
          for group in self.groups:
  
              if group.group_name == group_name:
                  return group
          return None
docs: Gets a group from its name
  
          Args:
              group_name:
  
          Returns: Group