gistfile1.txt

sync(ethereum, callback) {
    var promise
    promise = new Promise((resolve, reject) => {
      const acc = this.shallowClone()
      ethereum.getBalance(acc.address, (balance) => {
        acc.balance = balance
        resolve(acc)
      })
    })

    promise = promise.then((acc) => {
      return new Promise((resolve, reject) => {
        ethereum.getNonce(acc.address, (nonce) => {
          acc.nonce = nonce
          if (acc.nonce > acc.manualNonce) {
            acc.manualNonce = acc.nonce
          }
          resolve(acc)
        })
      })
    })

    Object.keys(this.tokens).forEach((key) => {
      promise = promise.then((acc) => {
        return new Promise((resolve, reject) => {
          acc.tokens[key].sync(ethereum, (token) => {
            acc.tokens[key] = token
            resolve(acc)
          })
        })
      })
    })

    promise.then((acc) => {
      callback(acc)
    })
  }