1><p><span class="helptopic">Vehicle driver class</span></p><p>
Create a "driver" object capable of steering a Vehicle object through random
waypoints within a rectangular region and at constant speed.

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<p>
The driver object is connected to a Vehicle object by the latter's
add_driver() method.  The driver's demand() method is invoked on every
call to the Vehicle's step() method.

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<h2>Methods</h2>
<table class="list">
  <tr><td style="white-space: nowrap;" class="col1"> init</td> <td>reset the rand