Extra links supported for operators coming from third-party packages:

airflow.serialization.serialized_objects.BUILTIN_OPERATOR_EXTRA_LINKS

airflow/cli/cli_parser.py
func=lazy_load_command('airflow.cli.commands.variable_command.variables_delete'),
        args=(ARG_VAR,),
    ),
    ActionCommand(
        name='import',
        help='Import variables',
        func=lazy_load_command('airflow.cli.commands.variable_command.variables_import'),
        args=(ARG_VAR_IMPORT,),
    ),
    ActionCommand(
        name='export',
        help='Export all variables',
        func=lazy_load_command('airflow.cli.commands.variable_command.variables_export'),
        args=(ARG_VAR_EXPORT,),
    ),
)
DB_COMMANDS = (
    ActionCommand(
        name='init',
        help="Initialize the metadata database",
        func=lazy_load_command('airflow.cli.commands.db_command.initdb'),
        args=(),
    ),
    ActionCommand(
        name="check-migrations",
        help="Check if migration have finished",
        description="Check if migration have finished (or continually check until timeout)",
        func=lazy_load_command('airflow.cli.commands.db_command.check_migrations'),
        args=(ARG_MIGRATION_TIMEOUT,),
    ),