 only the <code class="computeroutput"><span class="identifier">key_type</span></code>
        (<code class="computeroutput"><span class="identifier">domain_type</span></code>) but also an
        interval type and a set type can be <span class="emphasis"><em><span class="bold"><strong>key types</strong></span></em></span>,
        that allow for <span class="emphasis"><em><span class="bold"><strong>selection</strong></span></em></span>
        and <span class="emphasis"><em><span class="bold"><strong>remov