'ring the bell if requested.'

def _bell(self):

    if (self.bell_style == 'none'):
        pass
    elif (self.bell_style == 'visible'):
        raise NotImplementedError('Bellstyle    visible    is    not    implemented    yet.')
    elif (self.bell_style == 'audible'):
        self.console.bell()
    else:
        raise ReadlineError(('Bellstyle    %s    unknown.' % self.bell_style))
