anchor.diff:  open AnalysisUtils
   open System
   open System.IO
  +open System.Text.RegularExpressions
   
   module CodeGen =
       type Value = (string * string * string) // name, type, code
  
positive.code:             do! putState newEnv
              return (sprintf "%%_%d" newEnv.regCounter)
          }
  
  //    let append (code:string) : State<unit, Environment> =
  //        state {
  
negative.code: 
                              // get the address in the list
                              let! addrReg = freshReg
  
  
  
                              let regType = sprintf "%s*" (extractTypeListType toUpdateType)
                              let getElemCode = sprintf "getelementptr %s %s, i32 0, i32 %d" toUpdateType toUpdateName idx
                              let! (addrName, addrType, addrCode) = newRegister addrReg regType getElemCode
                              //  
  