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: descendant.rs
    path of file: ./repos/ckb/test/src/specs/tx_pool
    
    the code of the file until where you have to start completion: use ckb_jsonrpc_types::Status;

use crate::specs::tx_pool::utils::prepare_tx_family;
use crate::utils::{blank, commit, propose};
use crate::{Node, Spec};
use std::collections::HashSet;

// Convention:
//   * `tx_family` is a set of relative transactions, `tx_family.a <- tx_family.b <-
//     tx_family.c <- tx_family.d <- tx_family.e`, note that `x <- y` represents `x` is the parent
//     transaction of `y`.

pub struct HandlingDescendantsOfProposed;

impl Spec for HandlingDescend
    
    fn run(&self, nodes: &mut Vec<Node>) {
        let node = &nodes[0];
        let window = node.consensus().tx_proposal_window();
        node.mine(window.farthest() + 2);

        // 1. Propose `tx_family.a` and `tx_family.b` into pending-pool.
        let family = prepare_tx_family(node);
        node.submit_transaction(family.a());
        node.submit_transaction(family.b());

        // 2. Propose `tx_family.b`, but `tx_family.a` not, then continuously submit blank blocks.
        //    In the time, miner should not commit `tx_family.b` as its parent `tx_family.a` has
        //    not been not proposed and committed yet.
        node.submit_block(&propose(node, &[family.b()]));
        (0..window.closest()).for_each(|_| {
            node.submit_block(&blank(node)); // continuously submit blank blocks.
        });
        let block = node.new_block(None, None, None);
        assert_eq!(block.transactions()[1..], []);

        let block = commit(node, &[family.b()]);
        node.rpc_client()
            .submit_block("".to_string(), block.data().into())
            .expect_err("should be failed as it contains invalid transaction");
    }