Working with uasyncio

[maveric]

I was able to get this library working with uasyncio using the inputs as buttons with a very simple addition.

Adding:

def __call__(self):
        return self.value()

to the VirtualPin class allows extremely simple addition of inputs / buttons with asyncio - example:

from primitives import Pushbutton
import uasyncio as asyncio
import mcp23017
BLUE_INPUT_PIN = 0

...

mcp.pin(BLUE_INPUT_PIN, mode=1, pullup=1, polarity=1)
blue_button = Pushbutton(self.mcp[BLUE_INPUT_PIN])
blue_button.press_func(None)
asyncio.create_task(self.buttonPressed(self.blue_button.press, 'blue'))

I'm a github noob and don't know how to offer a pull request.