class="keyword">float</span></code>,
        <code class="computeroutput"><span class="keyword">double</span></code> and <code class="computeroutput"><span class="keyword">long</span>
        <span class="keyword">double</span></code>. The facet is case-insensitive.
        An optional + sign can be used with positive numbers. The dots in nan(...)
        stand for an arbitrary string usually containing the <span class="emphasis"><em>NaN payload</em></span>.
        Parsing of strings that represent integer