anchor.diff:      allDocsRaw includeDocs options props 
       |> asyncMap (stringToDocumentList props.converter)
   
  -let count = 
  -    allDocs WithoutDocs [ListLimit 0] 
  -    >> asyncMap (fun (totalRows, _, _) -> totalRows)
  -
  -let countByExpression () = failwith "Not implemented"
  -
  -let countByObject () = failwith "Not implemented"
  -
  -let countBySelector () = failwith "Not implemented"
  -
   let create document props = 
       request "" props
       |> body document
  
positive.code:     return docs
  }
  
  /// Retrieves a count of all documents matching the given selector.
  let countBySelector = convertMapToDict >> countByDictionary
  
  /// Checks that a document matching the given selector exists.
  let existsBySelector = convertMapToDict >> existsByDictionary
  
  let bulkInsert () = failwith "Not implemented"
  
  
negative.code:     // Doc exists if CouchDB didn't throw an error status code
      >> asyncMap (function | Choice1Of2 _ -> true | Choice2Of2 _ -> false) 
  
  let copy oldId newId props = 
      request oldId props
      |> headers (Map.ofSeq ["Destination", newId])
  