I need a piece of code that returns the close price of a certain candle after a trade is opened. "The order is still open". 
I want to know the price of different candles every time I run the EA.
this code must count the candles (according to the number I set in the expert specification everytime I run the expert) and returns that candle's close price NOT THE ORDER CLOSE PRICE.

it must be in the form of: 

double (pip-difference)
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return (pip-difference);

(or any of these sort of codes, i just wrote this as an example. you decide how it must be). 

Here is another example of what I want:
//================================================================================================
double LotsOptimized()
  {
   double lot=Lots;
   int    orders=HistoryTotal();     // history orders total
   int    losses=0;                  // number of losses orders without a break
//--- select lot size
   lot=NormalizeDouble(AccountFreeMargin()*MaximumRisk/1000.0,1);
//--- calcuulate number of losses orders without a break
   if(DecreaseFactor>0)
     {
      
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      if(losses>1)
         lot=NormalizeDouble(lot-lot*losses/DecreaseFactor,1);
     }
//--- return lot size
   if(lot<0.1) lot=0.1;
   return(lot);
  }
//=====================================================================================================


I want to call this function anywhere in the EA I want. So it must be a separeate function. 

it must work in all the mt4 experts. Just like the example above, It must return a value only.

Conditions: 

1. all the variables and things that this code needs must be inside itself. the only variable that is allowed to be outside of the code is 
"extern double candle_number = .... " which is the number of candles that i set every time i run my expert. 

Only this variable MUST be outside of the code and I put it in my expert( this is a MUST and is very important).

2. every time a trade is opened, this code must count the candles ( according to what I set for candle number) and returns the close price of the CANDLE (the order is still open). 

3.It gets only one input as "Extern Double" ( which I ditermine every time I run my expert and I should be able to change it anytime I want)

The only job this code must do is:

imagine I determine the candle_number=5, When a trade is opened, this code must return the close of the 5th candle from the trade open. 
If I set the candle_number = 13, any position that is opened, this code must return the 13th candle's close price. please see the images to get the exact idea.

Important note: I set the days of finishing this job for 5 days because of checking and revising, So please finish the code in 1-2 days so,
 we have enough time to test and revise it. In the testing and revising the code, I may add or delete some things from the code,like if I forgot something in the 
explanation above, so please accept that in advance.