# Michelson pseudo-code to transform from source script.
  # This transformation adds 'set_delegate' entrypoint, e.g.:
  #
  #  parameter <parameter_expr> ;
  #  storage <storage_expr> ;
  #  code <code_expr> ;
  #
  # to:
parameter
  (or
     (or (key_hash %set_delegate)
         (unit %remove_delegate))
     (or %default string nat)
  ) ;

storage
  (pair
     key_hash # manager
     (pair string nat)
  ) ;

code {
       DUP ;
       CAR ;
       IF_LEFT
         { # 'set_delegate'/'remove_delegate' entrypoints
           # Assert no token was sent:
           # to send tokens, the default entry point should be used
           PUSH mutez 0 ;
           AMOUNT ;
           ASSERT_CMPEQ ;
           # Assert that the sender is the manager
           DUP 2 ;
           CDR ;
           CAR ;
           IMPLICIT_ACCOUNT ; ADDRESS ;
           SENDER ;
           IFCMPNEQ
             { SENDER ;
               PUSH string "Only the owner can operate." ;
               PAIR ;
               FAILWITH ;
             }
             { DIP { CDR ; NIL operation } ;
               IF_LEFT
                 { # 'set_delegate' entrypoint
                   SOME ;
                   SET_DELEGATE ;
                   CONS ;
                   PAIR ;
                 }
                 { # 'remove_delegate' entrypoint
                   DROP ;
                   NONE key_hash ;
                   SET_DELEGATE ;
                   CONS ;
                   PAIR ;
                 }
             }
         }
         { # Transform the inputs to the original script types
           DIP { CDR ; DUP ; CDR } ;
           PAIR ;

           # 'default' entrypoint - original code
           { UNPAIR;
             IF_LEFT
               { DIP { UNPAIR ; DROP } }
               { DUG 1; UNPAIR ; DIP { DROP } } ;
             PAIR ; NIL operation ; PAIR }
           # Transform the outputs to the new script types (manager's storage is unchanged)
           SWAP ;
           CAR ;
           SWAP ;
           UNPAIR ;
           DIP { SWAP ; PAIR } ;
           PAIR ;
         }
     }