# File lib/parser/builders/default.rb, line 886
    def not_op(not_t, begin_t=nil, receiver=nil, end_t=nil)
      if @parser.version == 18
        n(:not, [ check_condition(receiver) ],
          unary_op_map(not_t, receiver))
      else
        if receiver.nil?
          nil_node = n0(:begin, collection_map(begin_t, nil, end_t))

          n(:send, [
            nil_node, '!''!'
          ], send_unary_op_map(not_t, nil_node))
        else
          n(:send, [ check_condition(receiver), '!''!' ],
            send_map(nil, nil, not_t, begin_t, [receiver], end_t))
        end
      end
    end