public ReplyHandler popHandler() {
        return callStack.pop(this);
    }
<p>This is a convenience method for calling {@link CallStack#pop(Routable)} on the {@link CallStack} of this
Routable. It equals calling <code>routable.getCallStack().pop(routable)</code>.</p>

@return The handler that was popped.
@see CallStack#pop(Routable)
messagebus/src/main/java/com/yahoo/messagebus/Routable.java