public Observable<Void> write(Observable<WebSocketFrame> msgs, Func1<WebSocketFrame, Boolean> flushSelector) {
        return delegate.write(msgs, flushSelector);
    }
public Observable < Void > write ( Observable < WebSocketFrame > msgs , Func1 < WebSocketFrame , Boolean > flushSelector ) { return delegate . write ( msgs , flushSelector ) ; }
On subscription of the returned {@link Observable}, writes the passed message stream on the underneath channel
and flushes the channel, everytime, {@code flushSelector} returns {@code true} . Any writes issued before
subscribing, will also be flushed. However, the returned {@link Observable} will not capture the result of those
writes, i.e. if the other writes, fail and this write does not, the returned {@link Observable} will not fail.

@param msgs Message stream to write.
@param flushSelector A {@link Func1} which is invoked for every item emitted from {@code msgs}. Channel is
flushed, iff this function returns, {@code true}.

@return An {@link Observable} representing the result of this write. Every
subscription to this {@link Observable} will write the passed messages and flush all pending writes, when the
{@code flushSelector} returns {@code true}