<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def progress_bar(name, maxval, prefix='Converting'):
 """Manages a progress bar for a conversion. Parameters name : str Name of the file being converted. maxval : int Total number of steps for the conversion. """

    widgets = ['{} {}: '.format(prefix, name), Percentage(), ' ',
               Bar(marker='=', left='[', right=']'), ' ', ETA()]
    bar = ProgressBar(widgets=widgets, max_value=maxval, fd=sys.stdout).start()
    try:
        yield bar
    finally:
        bar.update(maxval)
        bar.finish()