Traceback (most recent call last):
  File "line.py", line 504, in <module>
    sim.run()
  File "/usr/local/lib/python3.6/dist-packages/nmigen-72cf4ca-py3.6.egg/nmigen/back/pysim.py", line 820, in run
    while self.step():
  File "/usr/local/lib/python3.6/dist-packages/nmigen-72cf4ca-py3.6.egg/nmigen/back/pysim.py", line 789, in step
    self._update_dirty_signals()
  File "/usr/local/lib/python3.6/dist-packages/nmigen-72cf4ca-py3.6.egg/nmigen/back/pysim.py", line 633, in _update_dirty_signals
    funclet(self._state)
  File "/usr/local/lib/python3.6/dist-packages/nmigen-72cf4ca-py3.6.egg/nmigen/back/pysim.py", line 355, in run
    stmt(state)
  File "/usr/local/lib/python3.6/dist-packages/nmigen-72cf4ca-py3.6.egg/nmigen/back/pysim.py", line 347, in run
    body(state)
  File "/usr/local/lib/python3.6/dist-packages/nmigen-72cf4ca-py3.6.egg/nmigen/back/pysim.py", line 355, in run
    stmt(state)
  File "/usr/local/lib/python3.6/dist-packages/nmigen-72cf4ca-py3.6.egg/nmigen/back/pysim.py", line 346, in run
    if check(test_value):
  File "/usr/local/lib/python3.6/dist-packages/nmigen-72cf4ca-py3.6.egg/nmigen/back/pysim.py", line 332, in <lambda>
    return lambda test: prev_check(test) or test & mask == value
  File "/usr/local/lib/python3.6/dist-packages/nmigen-72cf4ca-py3.6.egg/nmigen/back/pysim.py", line 332, in <lambda>
    return lambda test: prev_check(test) or test & mask == value
  File "/usr/local/lib/python3.6/dist-packages/nmigen-72cf4ca-py3.6.egg/nmigen/back/pysim.py", line 332, in <lambda>
    return lambda test: prev_check(test) or test & mask == value
  [Previous line repeated 989 more times]
RecursionError: maximum recursion depth exceeded