sub scribble {
   while ( $a = shift ){
      $a; # has arg
   }
}

##</code><code>##

sub scribble {
   while ( $_ = shift ){
      $_; # has arg
   }
}

##</code><code>##

sub scribble {
   local $_;
   while ( $_ = shift ){
      $_; # has arg
   }
}