def METHOD_NAME(self, key: bytes) -> tuple[int, bytes]:
    """Parse a key on the column-family."""
    import struct
    assert len(key) == 4 + 32
    timestamp: int
    (timestamp,) = struct.unpack('>I', key[:4])
    tx_hash = key[4:]
    assert len(tx_hash) == 32
    return timestamp, tx_hash