anchor.diff:                          then None
                           else Some(Array.averageBy Option.get window))
   
  +/// Extensions for F#'s List module.
   module List =
       /// Curried cons
       let inline cons hd tl = hd::tl
  
positive.code:             pad (total - List.length list) elem list
  
  [<CompilationRepresentation(CompilationRepresentationFlags.ModuleSuffix)>]
  module Dictionary =
      let tryFind key (d: IDictionary<_,_>) =
          match d.TryGetValue key with
          | true,v -> Some v
          | _ -> None
  
  module Map =
      let spanWithKey pred map =
          map
  
negative.code: 
  [<CompilationRepresentation(CompilationRepresentationFlags.ModuleSuffix)>]
  [<Extension>]
  /// Extensions for NameValueCollections.
  module NameValueCollection =
      open System.Collections.Specialized
      open System.Linq
  