def METHOD_NAME(self):
    """Non-blocking lock aquisition. Returns True on success, False
    otherwise."""
    if self._held:
        return False
    try:
        Flock(self.LOCK_TYPE).fcntl(self.fd, fcntl.F_SETLK)
    except IOError as e:
        if e.errno in [errno.EACCES, errno.EAGAIN]:
            return False
        raise
    self._held = True
    return True