How to use pouchdb-adapter-leveldb-core - 5 common examples

/* istanbul ignore else */
  if (!leveldown) {
    leveldown = requireLeveldown();

    /* istanbul ignore if */
    if (leveldown instanceof Error) {
      return callback(leveldown);
    }
  }

  var _opts = Object.assign({
    db: leveldown,
    migrate: migrate
  }, opts);

  CoreLevelPouch.call(this, _opts, callback);
}

function CustomLevelPouch(opts, callback) {
    var _opts = assign({
      db: db
    }, opts);

    CoreLevelPouch.call(this, _opts, callback);
  }

function FruitDownPouch(opts, callback) {
  var _opts = Object.assign({
    db: fruitdown
  }, opts);

  CoreLevelPouch.call(this, _opts, callback);
}

function MemDownPouch(opts, callback) {
  var _opts = Object.assign({
    db: memdown
  }, opts);

  CoreLevelPouch.call(this, _opts, callback);
}

function LocalStoragePouch(opts, callback) {
  var _opts = Object.assign({
    db: localstoragedown
  }, opts);

  CoreLevelPouch.call(this, _opts, callback);
}