>>> from datetime import datetime
  >>> datetime.now()
  Traceback (most recent call last):
    File "<console>", line 1, in <module>
    File "/lib/pypyjs/lib_pypy/datetime.py", line 1548, in now
      return cls.fromtimestamp(t, tz)
    File "/lib/pypyjs/lib_pypy/datetime.py", line 1511, in fromtimestamp
      us = _round(frac * 1e6)
    File "/lib/pypyjs/lib_pypy/datetime.py", line 28, in _round
      return int(_math.floor(x + 0.5) if x >= 0.0 else _math.ceil(x - 0.5))
  ValueError: cannot convert float NaN to integer