anchor.diff:    (format stream "~&Jugadores:~t~{~a~^, ~}"
             (loop repeat (size (players game))
                   for p in (slot-value game 'players-round)
  -                collecting (if (equal p (turn-player game))
  +                collecting (if (equal p (name (turn-player game)))
                                (format nil "-~a-" p)
                                p)))
     (format stream "~&Etapa:~t~a" (state game))
  
positive.code:       (destination (territory game destination-key))
        (attackers (armies origin))
        (defenders (armies destination)))
       (unless (territories-connected-p game origin-key destination-key)
         (error "Los territorios deben estar conectados"))
       (unless (> attackers 2)
  
negative.code: (defgeneric place-armies (game where amount)
    (:method ((game game) territory-key (amount integer))
     (let ((territory (territory game territory-key)))
       (unless (eq (owner territory) (turn-player game))
         (error "El territorio debe pertenecer al jugador de turno"))
       (unless (> amount 0)
         (error "No se pueden poner 0 o menos ejércitos"))
       (unless (<= amount (pending-armies game))
  