C:\Steve\Dev\PerlMonks\P-2015-03-19@1121-Durable-Subroutine-Data>persistent1.pl
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SUB BEGIN:   $requestedValue = [Initial value]
SUB BEGIN:  $persistentValue = []
SUB BEGIN:      $returnValue = []
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  SUB END:   $requestedValue = [Initial value]
  SUB END:  $persistentValue = [Initial value]
  SUB END:      $returnValue = [<Initial value>]
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     MAIN:       $tossMeAbout = [Initial value]
     MAIN:      $updatedValue = [<Initial value>]
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SUB BEGIN:   $requestedValue = [<Initial value>]
SUB BEGIN:  $persistentValue = [Initial value]
SUB BEGIN:      $returnValue = []
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  SUB END:   $requestedValue = [<Initial value>]
  SUB END:  $persistentValue = [Initial value/<Initial value>]
  SUB END:      $returnValue = [<<Initial value>>]
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     MAIN:       $tossMeAbout = [Initial value]
     MAIN:      $updatedValue = [<Initial value>]
     MAIN:   $additionalValue = [<<Initial value>>]
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