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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 download_list(user=None, pwd=None, limit=20, offset=0):
 """ Lists the downloads created by a user. :param user: [str] A user name, look at env var ``GBIF_USER`` first :param pwd: [str] Your password, look at env var ``GBIF_PWD`` first :param limit: [int] Number of records to return. Default: ``20`` :param offset: [int] Record number to start at. Default: ``0`` Usage:: from pygbif import occurrences as occ occ.download_list(user = "sckott") occ.download_list(user = "sckott", limit = 5) occ.download_list(user = "sckott", offset = 21) """


    user = _check_environ('GBIF_USER', user)
    pwd = _check_environ('GBIF_PWD', pwd)

    url = 'http://api.gbif.org/v1/occurrence/download/user/' + user
    args = {'limit': limit, 'offset': offset}
    res = gbif_GET(url, args, auth=(user, pwd))
    return {'meta': {'offset': res['offset'],
                     'limit': res['limit'],
                     'endofrecords': res['endOfRecords'],
                     'count': res['count']},
            'results': res['results']}