import progressbar, time

widgets = [
    progressbar.Percentage(),
    progressbar.Bar(),
    progressbar.DynamicMessage('user'),
]
with progressbar.ProgressBar(max_value=100, widgets=widgets) as bar:
    for i in range(100):
        bar.update(i, user='me')
        time.sleep(0.2)`

def __call__(self, progress, data):
    val = data['dynamic_messages'][self.name]
    if val:
            if isinstance(val,str):
                return self.name + ': ' + '{:6s}'.format(val)
            else:
                return self.name + ': ' + '{:6.3g}'.format(val)
    else:
        return self.name + ': ' + 6 * '-'