='hljl-nf'>sir_sde!</span><span class='hljl-p'>(</span><span class='hljl-n'>du</span><span class='hljl-p'>,</span><span class='hljl-n'>u</span><span class='hljl-p'>,</span><span class='hljl-n'>p</span><span class='hljl-p'>,</span><span class='hljl-n'>t</span><span class='hljl-p'>)</span><span class='hljl-t'>
    </span><span class='hljl-p'>(</span><span class='hljl-n'>S</span><span class='hljl-p'>,</span><span class='hljl-n'>I</span><span class='hljl-p'>,</span><span class='hljl-n'>R</span><span class='hljl