          written to <em class="parameter"><code>params</code></em>.  For all other input and output variables, the value
            -1 is written to <em class="parameter"><code>params</code></em>.  For uniforms in uniform blocks, the value -1
            is written to <em class="parameter"><code>params</code></em>.
        </p>
        <p>
            For the property <code class="constant">GL_LOCATION_INDEX</code>, a single integer identifying the fragment
            color index of an active fragment sh