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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def get_themes(urls):
    '''takes in dict of names and urls, downloads and saves files'''

    length = len(urls)
    counter = 1
    widgets = ['Fetching themes:', Percentage(), ' ',
               Bar(marker='-'), ' ', ETA()]

    pbar = ProgressBar( widgets=widgets, maxval=length ).start()

    for i in urls.keys():
        href = 'http://dotshare.it/dots/%s/0/raw/' % urls[i]
        theme = urllib.urlopen(href).read()
        f = open(THEMEDIR + i, 'w')
        f.write(theme)
        f.close()
        pbar.update(counter)
        counter += 1

    pbar.finish()