;ckgabewert vom Wert des Schalters 
<code>prederror</code> bestimmt.
</p>
<pre class="example">(%i1) assume (a &gt; b);
(%o1)                        [a &gt; b]
(%i2) prederror: true$
(%i3) is (a &gt; 0);
Maxima was unable to evaluate the predicate:
a &gt; 0
 -- an error.  Quitting.  To debug this try debugmode(true);
(%i4) prederror: false$
(%i5) is (a &gt; 0);
(%o5)                        unknown
</pre></dd></dl>

<p><a name="killcontext"></a>
</p><dl>
<dt><u>Funktion:</u> <b>killcontext</b><i> (<var>conte