buffer.js

  function toArray(x) { return x.toArray(); }

  /**
   *  Projects each element of an observable sequence into zero or more buffers.
   *  @param {Mixed} bufferOpeningsOrClosingSelector Observable sequence whose elements denote the creation of new windows, or, a function invoked to define the boundaries of the produced windows (a new window is started when the previous one is closed, resulting in non-overlapping windows).
   *  @param {Function} [bufferClosingSelector] A function invoked to define the closing of each produced window. If a closing selector function is specified for the first parameter, this parameter is ignored.
   *  @returns {Observable} An observable sequence of windows.
   */
  observableProto.buffer = function () {
    return this.window.apply(this, arguments)
      .flatMap(toArray);
  };