rj@pollux:~/_ELRIC/implementation/src/examples> perl -MO=Xref -we 1
File -e
  Subroutine (definitions)
    Package UNIVERSAL
      &VERSION          s0
      &can              s0
      &isa              s0
    Package attributes
      &bootstrap        s0
-e syntax OK

##</code><code>##

Use of uninitialized value in string eq at /usr/lib/perl5/5.6.1/i586-linux/B/Xref.pm line 117.
Use of uninitialized value in substitution (s///) at /usr/lib/perl5/5.6.1/i586-linux/B/Xref.pm line 124.
Use of uninitialized value in string eq at /usr/lib/perl5/5.6.1/i586-linux/B/Xref.pm line 117.
Use of uninitialized value in substitution (s///) at /usr/lib/perl5/5.6.1/i586-linux/B/Xref.pm line 124.
Use of uninitialized value in concatenation (.) or string at /usr/lib/perl5/5.6.1/i586-linux/B/Xref.pm line 130.
Use of uninitialized value in string eq at /usr/lib/perl5/5.6.1/i586-linux/B/Xref.pm line 117.
etc. etc. (cut for node readability)
Use of uninitialized value in substitution (s///) at /usr/lib/perl5/5.6.1/i586-linux/B/Xref.pm line 124.
Use of uninitialized value in concatenation (.) or string at /usr/lib/perl5/5.6.1/i586-linux/B/Xref.pm line 130.
Use of uninitialized value in concatenation (.) or string at /usr/lib/perl5/5.6.1/i586-linux/B/Xref.pm line 130.

##</code><code>##

  Subroutine deflate
    Package (lexical)
      $$eref            51
      $@$$eref          56
      $@$@$$eref        60
      $@$@$@$$eref      65
      $@$@$@$@$$eref    70
      $eref             i50, 51
      $i                i55, 56, 59, 59, 55, 70, 71
      $inner            i60, 62, 63, 64, 55, 69
      $j                i59, 60, 65, 66, 67, 59
      $key              i49
      $outer            i56, 62, 63, 64, 55, 69
      $size             i51, 66, 59, 55, 71
      @$$eref           51, 56
      @$@$$eref         56, 60
      @$@$@$$eref       60, 65
      @$@$@$@$$eref     65, 70
      @$@$@$@$@$$eref   70
    Package main
      @_                49, 50