Missing unpipe function?

[EdoardoSchnell]

Hi, I was trying to call unpipe to disconnect two streams previously connected but the function appears to be missing.

Code to reproduce:

    const inputDevice = new midi.Input();
    inputDevice.openVirtualPort('test input port');
    const outputDevice = new midi.Output();
    outputDevice.openVirtualPort('test output port');
    const rs = midi.createReadStream(inputDevice);
    const ws = midi.createWriteStream(outputDevice);
    rs.pipe(ws);
    rs.unpipe(ws);

This leads to

    TypeError: rs.unpipe is not a function

so I guess it is not implemented? If you could add it it would be awesome :D