from nmigen import *
from nmigen.back.pysim import *

class Dummy(Elaboratable):
     def __init__(self):
        self.x = Signal()

     def elaborate(self, platform):
        return Module()

if __name__ == "__main__":
     dummy = Dummy()
     with Simulator(dummy) as sim:
        def process():
            yield dummy.x.eq(1)
            print((yield dummy.x))
            yield dummy.x.eq(0)
            print((yield dummy.x))
        sim.add_process(process)
        sim.run()