er, it is not passed
    any normal arguments, but it is passed a <span class="quote">“<span class="quote">context</span>”</span> pointer
    pointing to a <code class="structname">EventTriggerData</code> structure. C functions can
    check whether they were called from the event trigger manager or not by
    executing the macro:
</p><pre class="programlisting">
CALLED_AS_EVENT_TRIGGER(fcinfo)
</pre><p>
    which expands to:
</p><pre class="programlisting">
((fcinfo)-&gt;context != NULL &amp;&amp; IsA(