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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 namedb_get_account_tokens(cur, address):
 """ Get an account's tokens Returns the list of tokens on success Returns None if not found """

    sql = 'SELECT DISTINCT type FROM accounts WHERE address = ?;'
    args = (address,)

    rows = namedb_query_execute(cur, sql, args)
    ret = []
    for row in rows:
        ret.append(row['type'])

    return ret