The Abigail node is perfect, since it returns the value without modify it!

But if you want a pure Perl function for that:

sub eval_x {
  eval("die") ;
  my ($eval_x) = ( $@ =~ /\(\s*eval\s+(\d+)\s*\)/si );
  return( $eval_x ) ;
}
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The problem is that you make an eval to get the eval_x!

About the idea of "fever", to follow the order of the eval()s that you make to get the number, don't do this. Because if some eval() has another eval() inside, you can't follow any more!

Graciliano M. P.
"The creativity is the expression of the liberty".