anchor.diff:  method_or(#{self := Self} = Env, Object) ->
     Another = object_to_boolean(Object),
     RetVal = or_op(Self, Another),
  -  Env#{ret_val => RetVal}.
  +  erruby_rb:return(RetVal, Env).
   
   method_xor(#{self := Self} = Env, Object) ->
     Another = object_to_boolean(Object),
     NotAandB = and_op(not_op(Self),Another),
     AandNotB = and_op(Self, not_op(Another)),
     RetVal = or_op(NotAandB, AandNotB),
  -  Env#{ret_val => RetVal}.
  +  erruby_rb:return(RetVal, Env).
   
   method_true_to_s(Env) ->
     erruby_vm:new_string("true", Env).
  
positive.code:   erruby_object:def_method(TC, Name, Func),
    erruby_object:def_method(FC, Name, Func).
  
  new_true(Env) -> Env#{ret_val => true_instance()}.
  new_false(Env) -> Env#{ret_val => false_instance()}.
  
  true_instance() ->
    whereis(erruby_boolean_true).
  
negative.code:     True -> False;
      False -> True
    end,
    erruby_rb:return(RetVal, Env).
  
  method_and(#{self := Self} = Env, Object) ->
    Another = object_to_boolean(Object),
    RetVal = and_op(Self, Another),
    erruby_rb:return(RetVal, Env).
  
  object_to_boolean(Object) ->
    NilObject = erruby_nil:nil_instance(),
  