anchor.diff:      | KeyNotFound of key : string
       override this.ToString() = sprintf "%A" this
       interface IMessage with
  +        member this.LogProperty() = (MessageKeyword.Default, MessageLevel.Nothing)
  +            
           member this.OperationMessage() = 
               match this with
               | GreaterThan(fn, ll, v) -> sprintf "Field '%s' must be greater than %s, but found %s" fn ll v
  
positive.code:     | HttpNotSupported
      | HttpUriIdNotSupplied
      interface IMessage with
          member this.OperationMessage() = 
              match this with
              | HttpUnableToParse(e) -> sprintf "Unable to deserialize the HTTP body: \n%s" e
  
negative.code:     | NotImplemented
      | HeaderRowIsEmpty
      interface IMessage with
          member this.LogProperty() = (MessageKeyword.Node, MessageLevel.Info)
          member this.OperationMessage() = 
              match this with
              | UnableToUpdateMemory -> "Unable to update memory"
  