0;    <span class="keyword">using</span> value_type = T;</div>
<div class="line"><a name="l00038"></a><span class="lineno">   38</span>&#160;</div>
<div class="line"><a name="l00039"></a><span class="lineno">   39</span>&#160;    <span class="keyword">template</span>&lt;std::<span class="keywordtype">size_t</span> D&gt;</div>
<div class="line"><a name="l00040"></a><span class="lineno">   40</span>&#160;    <span class="keyword">struct </span>axis</div>
<div class="line"><a name="l00041"></a><span class="lin