nombre del método pasado como parámetro, corregir error, Prolog

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objeto :- write('{'),aux1, write('}').
valor(M):-read(Y),(Y='cadena'->cadena;
                 Y='numero'->numero;
                 Y='objeto'->objeto;
                 Y='arreglo'->arreglo;
                 Y='metodo'->metodo(M);
                 Y='true'->verdadero;
                 Y='false'->falso).
aux1 :- read(X),(X='atributo'->atributo;
                 X='fin'->write('')). 
atributo :-read(X),write('"'),write(X),write('"'), write(':'),valor(X),aux2.

aux2 :- read(X),(X='atributo'->write(','),atributo;
                 X='fin'->write('')). 
cadena :- read(X),write('"'),write(X),write('"').
numero :- read(N),write(N).
arreglo :- write('['),aux3,write(']').
aux3 :- read(X),(X='valor'->valor,aux4;
                 X='fin'->write('didid')).
aux4 :- read(X),(X='valor'->write(','),valor,aux4;
                 X='fin'->write('')). 
verdadero :- write('true').
falso :- write('false').
metodo(M) :- write('"function() {'),instruccion, write('return '),write(M),write('}"').
asignacion :- read(X),write(X),write('='),read(Y),write(Y),write(';').
aux5 :- read(X),(X='sinosi'->write('else '),decision;
                 X='sino'->write('else {'),instruccion,write('}');
                 X='fin'->write('')).
decision :- write('if ('),read(C),write(C),write(') {'),instruccion,write('}'),aux5.
instruccion :- read(I),(I='asignacion'->asignacion,instruccion;
                 I='decision' ->decision,instruccion;
                 I='fin'->write('')).

:- objeto.

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