anchor.diff:      Looping : Loop option;
       Ports : Port list ;
       Condition : Condition list;
  -    EXIT : bool;
  +    Assign : Assign list;
  +    Exit : bool;
   }
   
   type Proc = {
       Condition : Guard option;
  -    Port :  string;
  +    Port : string;
       ProcBody : ConditionBody
   }
   
  
positive.code:         AgentBody :  Agent;
  }
  
  type  Agents =  AlvisStatement list
  
  
  
  
negative.code:     | Const of bool
  
  
  type Assign =   ValueName
  
  
  type Alt =   Condition
  
  type SelectStatement = {
      Alt : Alt list;
  }
  
  type Loop = {
          Ports : Port list ;
          Exit : bool;
  