How to stagger div in xslt?

Question

XSL & XSLT

There is a task to deduce elements in a checkerboard pattern.

I can't reproduce it in xslt.
So far I've only come up with this:

<xsl:choose>
        <xsl:when test="position() mod 1 != 0 and position() mod 4 != 0">
            <div class="pego-columns pego-columns3 fl single-service-image">
                <xsl:if test="image_small != ''">
                    <img alt="{name}" src="{dir}{image_small}" class="attachment-full size-full" />
                </xsl:if>
            </div>
            <div class="pego-columns pego-columns3 fl single-service">
            <h1 class="service-title"><xsl:value-of disable-output-escaping="yes" select=" substring-before(name,' ')"/><span><xsl:value-of disable-output-escaping="yes" select=" substring-after(name,' ')"/></span></h1>
                <p class="service-excerpt"><xsl:value-of select="description" disable-output-escaping="yes" /></p>
            </div>
        </xsl:when>
        <xsl:otherwise> 
            <div class="pego-columns pego-columns3 fl single-service">
            <h1 class="service-title"><xsl:value-of disable-output-escaping="yes" select=" substring-before(name,' ')"/><span><xsl:value-of disable-output-escaping="yes" select=" substring-after(name,' ')"/></span></h1>
                <p class="service-excerpt"><xsl:value-of select="description" disable-output-escaping="yes" /></p>
            </div>
            <div class="pego-columns pego-columns3 fl single-service-image">
                <xsl:if test="image_small != ''">
                    <img alt="{name}" src="{dir}{image_small}" class="attachment-full size-full" />
                </xsl:if>
            </div>
        </xsl:otherwise>
    </xsl:choose>

turns out . And I don’t understand how to force all the elements to be arranged in a checkerboard pattern. Broke my whole head. Help comrades. Thank you.