'WSGI mini-app to create error output
By default, this just uses the \'error_status\', \'error_headers\',
and \'error_body\' attributes to generate an output page.  It can
be overridden in a subclass to dynamically generate diagnostics,
choose an appropriate message for the user\'s preferred language, etc.
Note, however, that it\'s not recommended from a security perspective to
spit out diagnostics to any old user; ideally, you should have to do
something special to enable diagnostic output, which is why we don\'t
include any here!'

def error_output(self, environ, start_response):

    start_response(self.error_status, self.error_headers[:], sys.exc_info())
    return [self.error_body]
