docs: def add_user(config, group, username):
          """Add specified user to specified group."""
          client = Client()
          client.prepare_connection()
          group_api = API(client)
          try:
              group_api.add_user(group, username)
          except ldap_tools.exceptions.NoGroupsFound:  # pragma: no cover
              print("Group ({}) not found".format(group))
          except ldap_tools.exceptions.TooManyResults:  # pragma: no cover
              print("Query for group ({}) returned multiple results.".format(
                  group))
          except ldap3.TYPE_OR_VALUE_EXISTS:  # pragma: no cover
              print("{} already exists in {}".format(username, group))