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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 subpacket_prefix_len(item):
 """Prefix subpacket length according to RFC 4880 section-5.2.3.1."""

    n = len(item)
    if n >= 8384:
        prefix = b'\xFF' + struct.pack('>L', n)
    elif n >= 192:
        n = n - 192
        prefix = struct.pack('BB', (n // 256) + 192, n % 256)
    else:
        prefix = struct.pack('B', n)
    return prefix + item