def METHOD_NAME(
    bitstrings: Sequence[Bitstring],
) -> npt.NDArray[np.float64]:
    """Converts a list of measured bitstrings to a probability vector estimated
    as the empirical frequency of each bitstring (ordered with increasing
    binary value).
    Args:
        bitstrings: All measured bitstrings.
    Returns:
        A probabiity vector corresponding to the measured bitstrings.
    """
    pv = np.zeros(2 ** len(bitstrings[0]))
    for bs in bitstrings:
        index = int("".join(map(str, bs)), base=2)
        pv[index] += 1
    pv /= len(bitstrings)
    return pv