You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: block_id.rs
    path of file: ./repos/bee/bee-block/tests
    
    the code of the file until where you have to start completion: // Copyright 2020-2021 IOTA Stiftung
// SPDX-License-Identifier: Apache-2.0

use core::str::FromStr;

use bee_block::BlockId;
use packable::PackableExt;

const BLOCK_ID: &str = "0x52fdfc072182654
    
fn pack_unpack_valid() {
    let block_id = BlockId::from_str(BLOCK_ID).unwrap();
    let packed_block_id = block_id.pack_to_vec();

    assert_eq!(packed_block_id.len(), block_id.packed_len());
    assert_eq!(
        block_id,
        PackableExt::unpack_verified(packed_block_id.as_slice(), &()).unwrap()
    );
}