def fileobj_open(filename, mode):
    """
    A wrapper around the `open()` builtin.

    This exists because `open()` returns an `io.BufferedReader` by default.
    This is bad, because `io.BufferedReader` doesn't support random access,
    which we need in some cases.  We must call open with buffering=0 to get
    a raw random-access file reader.
    """
    return open(filename, mode, buffering=0)
