SS_REQUIRE(type_var, ns, concept)</span></div><div class="line"><a name="l00053"></a><span class="lineno">   53</span>&#160;</div><div class="line"><a name="l00054"></a><span class="lineno">   54</span>&#160;    <span class="keyword">template</span> &lt;<span class="keyword">typename</span> C&gt;</div><div class="line"><a name="l00055"></a><span class="lineno">   55</span>&#160;    <span class="keywordtype">void</span> gil_function_requires() {}</div><div class="line"><a name="l00056"></a><span class="linen