Iterator.prg
 Array iterator functions
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     IEval( <nCount>, <bBlock> ) --> valueLast

     Evaluate <bBlock> <nCount> times, passing it the current iteration
     (starting at 1).  Return the value the last iteration returns.

     Collect( <aArray>, <bBlock> ) --> aResults

     Evaluate bBlock on each element of <aArray> and store the results in
     aResults.

     Extract( <aArray>, <bMatch> ) --> aMatches

     Returns the elements in <aArray> that match specified criteria.
     <bMatch> is passed one element at a time and should return true (.T.) if
     element matches criteria and false (.F.) otherwise.