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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 item_object_hook(dct):
 """ A custom object hook for use when decoding JSON item bodys. This hook will transform Amazon DynamoDB JSON responses to something that maps directly to native Python types. """

    if len(dct.keys()) > 1:
        return dct
    if 'S' in dct:
        return dct['S']
    if 'N' in dct:
        return convert_num(dct['N'])
    if 'SS' in dct:
        return set(dct['SS'])
    if 'NS' in dct:
        return set(map(convert_num, dct['NS']))
    return dct