'set modification time for the given path.  if \'mtime\' is None
(the default) then the file\'s mtime is set to current time.
Note that the resolution for \'mtime\' is platform dependent.'

def setmtime(self, mtime=None):

    if (mtime is None):
        return py.error.checked_call(os.utime, self.strpath, mtime)
    try:
        return py.error.checked_call(os.utime, self.strpath, ((-1), mtime))
    except py.error.EINVAL:
        return py.error.checked_call(os.utime, self.strpath, (self.atime(), mtime))
