/**
   * Return boolean indicating whether a memo id is valid
   *
   * @param memoId {String} memo id
   * @returns {boolean} true if memo id is valid
   */
  isValidMemoId(memoId) {
    try {
      stellar.Memo.id(memoId); // throws if the value is not valid memo id
      memoId = new BigNumber(memoId);
    } catch (e) {
      return false;
    }

    return (memoId.gte(0) && memoId.lt(maxMemoId));
  }

 /**
  * Evaluates whether a memo is valid
  *
  * @param value {String} value of the memo
  * @param type {String} type of the memo
  * @returns {Boolean} true if value and type are a valid
  */
 isValidMemo({ value, type }) {
   if (!value || !type) {
     return false;
   }
   try {
     // throws if the value is not valid for the type
     // valid types are: 'id', 'text', 'hash', 'return'
     // See https://www.stellar.org/developers/guides/concepts/transactions.html#memo
     stellar.Memo[type](value);
   } catch (e) {
     return false;
   }
   return true;
 }

const sourceKey = StellarSdk.Keypair.random(); // $ExpectType Keypair
const destKey = StellarSdk.Keypair.random();
const account = new StellarSdk.Account(sourceKey.publicKey(), '1');
const transaction = new StellarSdk.TransactionBuilder(account)
    .addOperation(StellarSdk.Operation.accountMerge({destination: destKey.publicKey()}))
    .addMemo(new StellarSdk.Memo(StellarSdk.MemoText, "memo"))
    .build(); // $ExpectType () => Transaction
transaction; // $ExpectType Transaction

StellarSdk.StellarTomlResolver.resolve("example.com", {allowHttp: true, timeout: 100})
    .then(toml => toml.FEDERATION_SERVER);

const sig = StellarSdk.xdr.DecoratedSignature.fromXDR(Buffer.of(1, 2)); // $ExpectType DecoratedSignature
sig.hint(); // $ExpectType Buffer
sig.signature(); // $ExpectType Buffer

StellarSdk.Memo.none(); // $ExpectType Memo<"none">
StellarSdk.Memo.text('asdf'); // $ExpectType Memo<"text">
StellarSdk.Memo.id('asdf'); // $ExpectType Memo<"id">
StellarSdk.Memo.return('asdf'); // $ExpectType Memo<"return">
StellarSdk.Memo.hash('asdf'); // $ExpectType Memo<"hash">
StellarSdk.Memo.none().value; // $ExpectType null
StellarSdk.Memo.id('asdf').value; // $ExpectType string
StellarSdk.Memo.text('asdf').value; // $ExpectType string
StellarSdk.Memo.return('asdf').value; // $ExpectType Buffer
StellarSdk.Memo.hash('asdf').value; // $ExpectType Buffer

// P.S. don't use Memo constructor
(new StellarSdk.Memo(StellarSdk.MemoHash, 'asdf')).value; // $ExpectType AnyValue
(new StellarSdk.Memo(StellarSdk.MemoHash, 'asdf')).type; // $ExpectType AnyType