# File lib/monkey/ext/object.rb, line 21
      def instance_yield(block = nil, &alternate_block)
        raise ArgumentError, "too many blocks given" if block && alternate_block
        block ||= alternate_block
        raise LocalJumpError, "no block given (yield)" unless block
        block.arity > 0 ? yield(self) : instance_eval(&block)
      end