[solved]How to add input variable in plugin

Questions
1

For example : let’s say i have a function block with Random number with an output variable

how I can add input variable block at my plugin that takes the output variable and do stuff to it

what I’m trying to do →
simple sum plugin , takes the output variable name from the function block , then sum number and output the equation to another output variable

2

Took me a while to understand the sourcecode , I will answer my own question here in case if someone has the same question

public block();  
      [Text("input variable", "The input variable name")]
      public string inVar { get; set; } = "";
      public string InVar { get { return inVar; } set { inVar = value; OnPropertyChanged(); } }
		
		
public FromLS()	
InVar = LineParser.ParseLiteral(ref input, "input variable");



public ToLS()
  var writer = new BlockWriter(GetType(), indent, Disabled)
   .Literal(InVar);
   
 public process()
 var single = data.Variables.GetSingle(InVar);