def open_if_exists(filename, mode='rb'):
    """Returns a file descriptor for the filename if that file exists,
    otherwise `None`.
    """
    try:
        return open(filename, mode)
    except IOError as e:
        if (errno.ENOENT, errno.EISDIR) not in e.errno:
            raise
dataset/ETHPy150Open lavr/python-emails/emails/loader/local_store.py/open_if_exists/swapped operands of `not in`