Horizontally stack a sequence of value bounds pairs.

    Parameters
    ----------
    tup: sequence
        a sequence of value, ``Bound`` pairs

    Returns
    -------
    value: ndarray
        a horizontally concatenated array1d
    bounds:
        a list of Bounds

def hstack(tup):
    """
    Horizontally stack a sequence of value bounds pairs.

    Parameters
    ----------
    tup: sequence
        a sequence of value, ``Bound`` pairs

    Returns
    -------
    value: ndarray
        a horizontally concatenated array1d
    bounds:
        a list of Bounds
    """
    vals, bounds = zip(*tup)
    stackvalue = np.hstack(vals)
    stackbounds = list(chain(*bounds))

    return stackvalue, stackbounds