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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 consume_item(rlp, start):
 """Read an item from an RLP string. :param rlp: the rlp string to read from :param start: the position at which to start reading :returns: a tuple ``(item, per_item_rlp, end)``, where ``item`` is the read item, per_item_rlp is a list containing the RLP encoding of each item and ``end`` is the position of the first unprocessed byte """

    p, t, l, s = consume_length_prefix(rlp, start)
    return consume_payload(rlp, p, s, t, l)