anchor.diff:  [<Name("substr"); Sealed>]
   type SubstrFunc() =
       interface IFlexQueryFunction with
  -        member __.GetVariableResult(_,_,_,_,_) = 
  +        member __.GetVariableResult(_,_,_,_) = 
               fail <| VariableFunctionNotSupported (__.GetType() |> getTypeNameFromAttribute) 
           member __.GetConstantResult(parameters, queryFunctionTypes, source) = 
               try
  
positive.code: [<Name("len"); Sealed>]
  type LenFunc() =
      interface IFlexQueryFunction with
          member __.GetVariableResult(_,_,_,_,_) = 
              fail <| VariableFunctionNotSupported (__.GetType() |> getTypeNameFromAttribute) 
          member __.GetConstantResult(parameters, queryFunctionTypes, source) = 
              try
  
negative.code:     let inline queryNotFound queryName = QueryNotFound <| queryName
      let inline fieldNotFound fieldName = InvalidFieldName <| fieldName
  
      let getQueryFunction (functions : Dictionary<string, IFlexQueryFunction>) funcName =
          match functions.TryGetValue(funcName) with
          | true, func -> ok func
          | _ -> fail <| FunctionNotFound funcName
  
      let handleFunctionValue fName 
                              parameters 
                              (queryFunctionTypes : Dictionary<string, IFlexQueryFunction>) 
                              (source : Dictionary<string,string> option) =
          fName |> getQueryFunction queryFunctionTypes
          >>= fun func ->
                  match func.GetConstantResult(parameters, queryFunctionTypes, source) with
                  | Ok(r) -> ok <| r
                  | Fail(e) -> fail e
  
      // Gets a field from the given search profile.
      // Empty/blank values are considered an error
  