ping is performed. 
    </li>
    <li><strong>execute_queries</strong>: one or more queries to execute per loop iteration.
    	<br/>Queries are separated by semicolons (<strong>;</strong>). See <a href="exec.html">exec()</a> for 
    	details.
    </li>
    <li><strong>stop_condition</strong>: the condition by which the loop terminates. Can be in one
    	of several forms and formats:
    	<ul>
    		<li><strong>NULL</strong>: no stop condition. The loop is infinite.</li>
    		<li><strong>0</strong>: The 