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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():
 """ return list of available themes """

    styles_dir = os.path.join(package_dir, 'styles')
    themes = [os.path.basename(theme).replace('.less', '')
              for theme in glob('{0}/*.less'.format(styles_dir))]
    return themes