> <span class="identifier">pi</span> <span class="special">=</span> <span class="number">3.141592653589793238462643383279502884e+00F</span><span class="special">;</span>
    <span class="special">}</span>
    <span class="keyword">namespace</span> <span class="identifier">double_constants</span>
    <span class="special">{</span>
      <span class="keyword">static</span> <span class="keyword">const</span> <span class="keyword">double</span> <span class="identifier">pi</span> <span class="special">=</span> <