Long story, ... you know meta-programming and syntactic sugar stuff. ;)

For instance I want to be able to automatically localize special package vars in a code-block

sub xsub (&) {
    my ($code)=@_;
    sub {
         local ($a,$b) = @_;
         &$code;
    }
}

my $c_ref = xsub { $a ** $b };

say $c_ref->(2,3);            #> 8
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This looks better than sub { $_[0] ** $_[1] }