sub evaluate {
  ($_)=@_;  
  my %oldexpressions=();
  while (!$oldexpressions{$_}) {
    $oldexpressions{$_}=1;
    $_ =~s/((?:\$|\&)(?:[\#|\$]*[A-Za-z][\w]*|\{[A-Za-z][\w]*\}))([\[|\{][\w\'\"]+[\]\}])*?(\([\w\'\"]+\))*?(?=[^\[\{\(]|$)/eval(defined(eval($1.$2))?eval('$1.$2.$3'):'$1.$2.$3')/seg;
  }
}