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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_platforms_set():
    '''Returns set of all possible platforms'''
    # arch and mageia are not in Py2 _supported_dists, so we add them manually
    # Ubuntu adds itself to the list on Ubuntu
    platforms = set([x.lower() for x in platform._supported_dists])
    platforms |= set(['darwin', 'arch', 'mageia', 'ubuntu'])
    return platforms