Computes Lin's similarity measure using pre-calculated Resnik's similarities.

def lin_sim_calc(goid1, goid2, sim_r, termcnts):
    '''
        Computes Lin's similarity measure using pre-calculated Resnik's similarities.
    '''
    if sim_r is not None:
        info = get_info_content(goid1, termcnts) + get_info_content(goid2, termcnts)
        if info != 0:
            return (2*sim_r)/info