How to use the web3-provider-engine/subproviders/provider function in web3-provider-engine

this.signMessage(...args);
        }
      })
    );

    !shareNonce
      ? this.engine.addProvider(new NonceSubProvider())
      : this.engine.addProvider(singletonNonceSubProvider);

    this.engine.addProvider(new FiltersSubprovider());
    if (typeof provider === "string") {
      // shim Web3 to give it expected sendAsync method. Needed if web3-engine-provider upgraded!
      // Web3.providers.HttpProvider.prototype.sendAsync =
      // Web3.providers.HttpProvider.prototype.send;
      this.engine.addProvider(
        new ProviderSubprovider(
          // @ts-ignore
          new Web3.providers.HttpProvider(provider, { keepAlive: false })
        )
      );
    } else {
      this.engine.addProvider(new ProviderSubprovider(provider));
    }
    this.engine.start(); // Required by the provider engine.
  }

? this.engine.addProvider(new NonceSubProvider())
      : this.engine.addProvider(singletonNonceSubProvider);

    this.engine.addProvider(new FiltersSubprovider());
    if (typeof provider === "string") {
      // shim Web3 to give it expected sendAsync method. Needed if web3-engine-provider upgraded!
      // Web3.providers.HttpProvider.prototype.sendAsync =
      // Web3.providers.HttpProvider.prototype.send;
      this.engine.addProvider(
        new ProviderSubprovider(
          // @ts-ignore
          new Web3.providers.HttpProvider(provider, { keepAlive: false })
        )
      );
    } else {
      this.engine.addProvider(new ProviderSubprovider(provider));
    }
    this.engine.start(); // Required by the provider engine.
  }

static getWeb3Instance() {
    const wallet = this.getWallet();

    const engine = new ProviderEngine();

    engine.addProvider(new WalletSubprovider(wallet, {}));
    engine.addProvider(new ProviderSubprovider(this.getWeb3HTTPProvider()));

    engine.start();

    const web3 = new Web3(engine);

    web3.eth.defaultAccount = wallet.getAddressString();

    return web3;
  }