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src/site/_includes/language-tour/control-flow/index.markdown

 You can control the flow of your Dart code using any of the following:
 
 * [If and else](#if-else)
 * [For loops](#for-loops)
 * [While and do while](#while)
 * [Break and continue](#break)
 * [Switch and case](#switch)
 * [Assert](#assert)
 
 <h4 id="if-else">If and else</h4>
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 if a [boolean](#booleans) condition is false.
 You can find examples of assert statements throughout this tour.
 Here are some more:
 
 {% highlight dart %}
 assert(text != null);  // Make sure the variable has a non-null value.
 assert(number < 100);  // Make sure the value is less than 100.
 assert(urlString.startsWith('https')); // Make sure this is an HTTPS URL.
 {% endhighlight %}
 
-<aside class="note" markdown="1">
-  **Important:** Assert statements work only in checked mode.
-  They have no effect in production mode.
+<aside>
+  <div class="alert alert-info">
+    <strong>Tip:</strong>
+    Assert statements work only in checked mode.
+    They have no effect in production mode.
+  </div>
 </aside>
 
 Inside the parentheses, you can put any expression
 that resolves to a boolean value.
 If the expression's value is true,
 the assertion succeeds and execution continues.
 Otherwise,
 the assertion fails and an exception (an
 [AssertionError](http://api.dartlang.org/dart_core/AssertionError.html))
 is thrown.