/**
  Request is a demo element.
  \color #740
  \symbol Rq
  \symmetries all
*/
element Request{
  DebugUtils du;
  EventWindow ew;
  AtomUtils au;
  Random rm;
  Unsigned(5) density;
  Unsigned(5) pvdrcnt;
  Void diffuse(){
    if(ew[1] is Empty){
      ew.swap(0,1);
    }
  }
  Void chkDense(){
    WindowServices ws;
    ws.reset(0,4);
    Signal s;
    Provider p;
    Int st =au.getType((Atom) s);
    Int pt =au.getType((Atom) p);
    if(ws.scan(st,pt)){  // observe either Providers or Signals around me.
      density=ws.getHits(0);
      pvdrcnt=ws.getHits(1);
      if (pvdrcnt>0){    // if Provider exists, I will disappear.
        Empty e;
        ew[0]=e;
      }else{
          diffuse();     // if no Provider, I walk away and store the number of Signals I observed.
      }
    }
    else diffuse();      // if neither Provider or Signal appears, I walk away.
  }

  Void behave(){
    chkDense();
  }
}