def METHOD_NAME():
    client = boto3.client("ebs", region_name="ap-southeast-1")
    snapshot_id1 = client.start_snapshot(VolumeSize=415)["SnapshotId"]
    snapshot_id2 = client.start_snapshot(VolumeSize=415)["SnapshotId"]
    for idx, data in [(1, b"data 1"), (2, b"data 2"), (3, b"data 3")]:
        checksum = hashlib.sha256(data).hexdigest()
        client.put_snapshot_block(
            SnapshotId=snapshot_id1,
            BlockIndex=idx,
            BlockData=data,
            DataLength=524288,
            Checksum=checksum,
            ChecksumAlgorithm="SHA256",
        )
    for idx, data in [(1, b"data 1.1"), (2, b"data 2"), (4, b"data 3.1")]:
        checksum = hashlib.sha256(data).hexdigest()
        client.put_snapshot_block(
            SnapshotId=snapshot_id2,
            BlockIndex=idx,
            BlockData=data,
            DataLength=524288,
            Checksum=checksum,
            ChecksumAlgorithm="SHA256",
        )
    resp = client.list_changed_blocks(
        FirstSnapshotId=snapshot_id1, SecondSnapshotId=snapshot_id2
    )
    changed_blocks = resp["ChangedBlocks"]
    changed_idxes = [b["BlockIndex"] for b in changed_blocks]
    assert changed_idxes == [1, 3]
    assert "FirstBlockToken" in changed_blocks[0]
    assert "SecondBlockToken" in changed_blocks[0]
    assert "FirstBlockToken" in changed_blocks[1]
    assert "SecondBlockToken" not in changed_blocks[1]