code: function Contract(config) {
        _classCallCheck(this, Contract);
  
        this._config = config;
        this._web3 = config.web3;
        this._bytecode = config.contract.bytecode;
        this._interface = JSON.parse(config.contract.interface);
        this._contract = this._web3.eth.contract(this._interface);
        this._account = config.account;
        this._gas = config.gas;
        this._logger = DUMMY_LOGGER;
      }
docs: Constuct a new instance.
  
  @param {Object} config Configuration.
  @param {Object} config.web3 A `Web3` instance.
  @param {Object} contract.contract Contract data, usually the output of `solc` compiler.
  @param {String} config.contract.interface Contract ABI interface JSON.
  @param {String} config.contract.bytecode Contract bytecode string.
  @param {Object} config.account Address of account to send transactions from.
  @param {Number} config.gas Gas amount to use for calls.