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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 standard_parsing_functions(Block, Tx):
 """ Return the standard parsing functions for a given Block and Tx class. The return value is expected to be used with the standard_streamer function. """

    def stream_block(f, block):
        assert isinstance(block, Block)
        block.stream(f)

    def stream_blockheader(f, blockheader):
        assert isinstance(blockheader, Block)
        blockheader.stream_header(f)

    def stream_tx(f, tx):
        assert isinstance(tx, Tx)
        tx.stream(f)

    def parse_int_6(f):
        b = f.read(6) + b'\0\0'
        return struct.unpack(b, "<L")[0]

    def stream_int_6(f, v):
        f.write(struct.pack(v, "<L")[:6])

    more_parsing = [
        ("A", (PeerAddress.parse, lambda f, peer_addr: peer_addr.stream(f))),
        ("v", (InvItem.parse, lambda f, inv_item: inv_item.stream(f))),
        ("T", (Tx.parse, stream_tx)),
        ("B", (Block.parse, stream_block)),
        ("z", (Block.parse_as_header, stream_blockheader)),
        ("1", (lambda f: struct.unpack("B", f.read(1))[0], lambda f, v: f.write(struct.pack("B", v)))),
        ("6", (parse_int_6, stream_int_6)),
        ("O", (lambda f: True if f.read(1) else False,
               lambda f, v: f.write(b'' if v is None else struct.pack("B", v)))),
    ]
    all_items = list(STREAMER_FUNCTIONS.items())
    all_items.extend(more_parsing)
    return all_items