Dict.prg
 Keyed dictionary utility
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     DictNew() --> aDictionary

     Creates and returns an empty dictionary.

     DictAt( <aDictionary>, <cKey> ) --> xValue

     Returns the value associated with <xKey> in dictionary, NIL if <cKey> is
     not present in dictionary.

     DictPut( <aDictionary>, <cKey>, <xValue> ) --> xValue

     Associates <cKey> to <xValue> in <aDictionary>.

     DictPutPair( <aDictionary>, <aPair> ) --> aPair

     Adds <aPair> to <aDictionary>.  <aPair> is a key/value pair: { <cKey>,
     <xValue> }.

     DictRemove( <aDictionary>, <cKey> ) --> aDictionary

     Removes the key/value pair for <cKey>.

     DictEval( <aDictionary>, <bBlock> ) --> aDictionary

     Evaluates <bBlock> against each <cKey>/<xValue> pair in dictionary. Pair
     is passed to block as { <cKey>, <xValue> }  (pair array indexes defined
     in "dict.ch").