environment/lib/python2.7/site-packages/IPython/config/application.py
def catch_config_error(method, app, *args, **kwargs):
    """Method decorator for catching invalid config (Trait/ArgumentErrors) during init.

    On a TraitError (generally caused by bad config), this will print the trait's
    message, and exit the app.
    
    For use on init methods, to prevent invoking excepthook on invalid input.
    """
    try:
        return method(app, *args, **kwargs)
    except (TraitError, ArgumentError) as e:
        app.print_description()
        app.print_help()
        app.print_examples()
        app.log.fatal("Bad config encountered during initialization:")
        app.log.fatal(str(e))
        app.log.debug("Config at the time: %s", app.config)
        app.exit(1)
def catch_config_error(method, app, *args, **kwargs):
    """Method decorator for catching invalid config (Trait/ArgumentErrors) during init.

    On a TraitError (generally caused by bad config), this will print the trait's
    message, and exit the app.
    
    For use on init methods, to prevent invoking excepthook on invalid input.
    """
    try:
        return method(app, *args, **kwargs)
    except (TraitError, ArgumentError) as e:
        app.print_description()
        app.print_help()
        app.print_examples()
        app.log.fatal("Bad config encountered during initialization:")
        app.log.fatal(str(e))
        app.log.debug("Config at the time: %s", app.config)
        app.exit(1)
Method decorator for catching invalid config (Trait/ArgumentErrors) during init.

    On a TraitError (generally caused by bad config), this will print the trait's
    message, and exit the app.
    
    For use on init methods, to prevent invoking excepthook on invalid input.