s{  ( [a-zA-Z]+ (?: ' [a-zA-Z]{1,2} )? )  }{

    exists $dict{ lc( $1 ) } ? $1 : "<@>$1";

    }exg;

##</code><code>##

s{  ( [a-zA-Z]+ (?: ' [a-zA-Z]{1,2} )? )  }{

    my $x = $1;
 
    exists $dict{ lc( $x ) } ? $1 : "<@>$1";

    }exg;

##</code><code>##

s{  ( [a-zA-Z]+ (?: ' [a-zA-Z]{1,2} )? )  }{

    my $x = $1;
 
    $x =~ s/'s\z//;

    exists $dict{ lc( $x ) } ? $1 : "<@>$1";

    }exg;

##</code><code>##

Use of uninitialized value in substitution iterator at ...