oint number
      in hexadecimal notation.</li>
<li><code class="code"><span class="constructor">F</span></code>: reads a floating point number according to the lexical
      conventions of OCaml (hence the decimal point is mandatory if the
      exponent part is not mentioned).</li>
<li><code class="code"><span class="constructor">B</span></code>: reads a boolean argument (<code class="code"><span class="keyword">true</span></code> or <code class="code"><span class="keyword">false</span></code>).</li>
<li>