def rectangle(target, throat_length='throat.length', throat_diameter=
    'throat.diameter'):
    """
    Calculate throat volume assuing a rectangular shape

    Parameters
    ----------
    target : OpenPNM Object
        The object which this model is associated with. This controls the
        length of the calculated array, and also provides access to other
        necessary properties.

    throat_length and throat_diameter : strings
        The dictionary keys containing the arrays with the throat diameter and
        length values.

    Notes
    -----
    At present this models does NOT account for the volume reprsented by the
    intersection of the throat with a spherical pore body.
    """
    return target[throat_length] * target[throat_diameter]
