Content:
teach

$remove bead *:
 @ifelse
  [setq(d,u(ATTACHED_%0))]
  [and(u(is.owner,%#),gt(strlen(%qd),0))]=
  {
   give %#=%qd;
   @pemit me={[wipe(me/ATTACHED_%0)]}
  },
  {
   @pemit %#={You can't.}
  }

One line version:

teach$remove bead *:@ifelse[setq(d,u(ATTACHED_%0))][and(u(is.owner,%#),gt(strlen(%qd),0))]={give %#=%qd;@pemit me={[wipe(me/ATTACHED_%0)]}},{@pemit %#={You can't.}}