code: func opcode1Add(op *parsedOpcode, vm *Engine) error {
  	m, err := vm.dstack.PopInt()
  	if err != nil {
  		return err
  	}
  
  	vm.dstack.PushInt(m + 1)
  	return nil
  }
docs: // opcode1Add treats the top item on the data stack as an integer and replaces
  // it with its incremented value (plus 1).
  //
  // Stack transformation: [... x1 x2] -> [... x1 x2+1]