interface IFunctionCallAssignment
{
  in void evt();
  out void actTrue();
  out void actFalse();
  
  behaviour 
  {
    bool b = false;
    on evt:
      b = func(b);
      
    bool func(bool c)
    {
      if (c) actTrue;
      else   actFalse;
      return !c;
    }
  }
}