def get_iscam_mws(intensities, mw_intensity_line_pars=None):
    """
    Calculate the molecular weights of the intensities with the line parameters
    `mw_intensity_line_pars`

    Parameters
    ----------
    intensities : np.ndarray
        inensities of an iscam measurements
    mw_intensity_line_pars : array like
        [slope, intercept] of the mw to intensities linear function.
    """
    mw_intensity_line_pars = [1, 0] if mw_intensity_line_pars is None \
        else mw_intensity_line_pars
    slope, intercept = mw_intensity_line_pars
    mws = (intensities - intercept) / slope
    return mws