anchor.diff:      client.ExistsAsync(id, Option.toObj rev)
       |> Async.AwaitTask
   
  +let private existsByDictionary selector props =
  +    let client = toClient props
  +
  +    client.ExistsBySelectorAsync selector
  +    |> Async.AwaitTask
  +
   /// Checks that a document matching the given selector exists.
  -let existsByMap (m: Map<string, obj>) props =
  -    let client = toClient props
  -
  -    client.ExistsBySelector m
  -    |> Async.AwaitTask
  +let existsBySelector = convertMapToDict >> existsByDictionary
   
   /// Checks that a document matching the given selector exists.
   /// Usage: existsByExpr<DocType> (<@ fun (c: DocType) -> c.SomeProp = SomeValue @>)
   /// NOTE: Davenport currently only supports simple 1 argument selectors.
  -let existsByExpr<'doctype> (selector: Expr<('doctype -> bool)>) props =
  -    let client = toClient props
  -    let expr = toLinq selector
  -
  -    client.ExistsBySelector expr
  -    |> Async.AwaitTask
  -
  -/// Checks that a document matching the given selector exists.
  -let existsByMapExpr<'doctype> map props =
  -    let client = toClient props
  -    let selector = convertMapExpr map
  -
  -    client.ExistsBySelector selector
  -    |> Async.AwaitTask+let existsByExpr<'doctype> = convertExprToMap<'doctype> >> existsByDictionary
  
positive.code:     client.CountAsync()
      |> Async.AwaitTask
  
  /// Retrieves a count of all documents matching the given selector.
  let countByMap (selector: Map<string, obj>) props =
      let client = toClient props
  
      client.CountBySelectorAsync selector
      |> Async.AwaitTask
  
  /// Retrieves a count of all documents matching the given selector.
  /// Usage: countByExpr<DocType> (<@ fun (c: DocType) -> c.SomeProp = SomeValue @>)
  /// NOTE: Davenport currently only supports simple 1 argument selectors.
  let countByExpr (selector: Expr<('doctype -> bool)>) props =
      let client = toClient props
      let expr = toLinq selector
  
      client.CountBySelectorAsync(expr)
      |> Async.AwaitTask
  
  /// Retrieves a count of all documents matching the given selector.
  let countByMapExpr map props =
      let client = toClient props
      let selector = convertMapExpr map
  
      client.CountBySelectorAsync(selector)
      |> Async.AwaitTask
  
  /// Checks whether a document with the given id exists. If a revision is given, it will check whether that specific version exists.
  let exists id (rev: string option) props =
  
negative.code: 
      newRow
  
  let private convertMapToDict (map: Map<string, Find>) =
      Map.map (fun _ (value: Find) -> value.ToFindExpression()) map
      |> Map.toSeq
      |> dict
  