Deploy WETH contract

import json

from eth_utils import encode_hex
from web3 import HTTPProvider, Web3
from solc import compile_source
from web3.contract import ConciseContract


# Solidity source code
contract_source_code = '''
pragma solidity ^0.4.18;

contract WETH9 {
    string public name     = "Wrapped Ether";
    string public symbol   = "WETH";
    uint8  public decimals = 18;

    event  Approval(address indexed src, address indexed guy, uint wad);
    event  Transfer(address indexed src, address indexed dst, uint wad);
    event  Deposit(address indexed dst, uint wad);
    event  Withdrawal(address indexed src, uint wad);

    mapping (address => uint)                       public  balanceOf;
    mapping (address => mapping (address => uint))  public  allowance;

    function() public payable {
        deposit();
    }
    function deposit() public payable {
        balanceOf[msg.sender] += msg.value;
        Deposit(msg.sender, msg.value);
    }
    function withdraw(uint wad) public {
        require(balanceOf[msg.sender] >= wad);
        balanceOf[msg.sender] -= wad;
        msg.sender.transfer(wad);
        Withdrawal(msg.sender, wad);
    }

    function totalSupply() public view returns (uint) {
        return this.balance;
    }

    function approve(address guy, uint wad) public returns (bool) {
        allowance[msg.sender][guy] = wad;
        Approval(msg.sender, guy, wad);
        return true;
    }

    function transfer(address dst, uint wad) public returns (bool) {
        return transferFrom(msg.sender, dst, wad);
    }

    function transferFrom(address src, address dst, uint wad)
        public
        returns (bool)
    {
        require(balanceOf[src] >= wad);

        if (src != msg.sender && allowance[src][msg.sender] != uint(-1)) {
            require(allowance[src][msg.sender] >= wad);
            allowance[src][msg.sender] -= wad;
        }

        balanceOf[src] -= wad;
        balanceOf[dst] += wad;

        Transfer(src, dst, wad);

        return true;
    }
}
'''

compiled_sol = compile_source(contract_source_code) # Compiled source code
contract_interface = compiled_sol['<stdin>:WETH9']

# web3.py instance
w3 = Web3(HTTPProvider("http://127.0.0.1:8545"))

# set pre-funded account as sender
w3.eth.defaultAccount = w3.eth.accounts[0]

# Instantiate and deploy contract
weth = w3.eth.contract(abi=contract_interface['abi'], bytecode=contract_interface['bin'])

# Submit the transaction that deploys the contract
tx_hash = weth.constructor().transact()
print(f"Transaction hash: {encode_hex(tx_hash)}")
# Wait for the transaction to be mined, and get the transaction receipt
tx_receipt = w3.eth.waitForTransactionReceipt(tx_hash)
print(tx_receipt)

# Create the contract instance with the newly-deployed address
weth_proxy = w3.eth.contract(
    address=tx_receipt.contractAddress,
    abi=contract_interface['abi'],
)
reader = ConciseContract(weth_proxy)
assert reader.symbol() == "WETH"
assert reader.name() == "Wrapped Ether"
assert reader.decimals() == 18