an></pre>
<div class="block"><p>
 This class is used to customize the way an ExpressionEvaluator resolves variable references at evaluation time. For
 example, instances of this class can implement their own variable lookup mechanisms, or introduce the notion of
 "implicit variables" which override any other variables. An instance of this class should be passed when evaluating
 an expression.
 </p>

 <p>
 An instance of this class includes the context against which resolution will happen
 </p></div>
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