anchor.diff:  
   module Features = 
   
  +    open System
  +    open System.Text.RegularExpressions
       open HomeDepot.Model
  +    open FParsec
   
       type Feature = Observation -> float
   
  
positive.code:         |> Seq.map (fun m -> m.Value)
          |> Set.ofSeq
  
      (*
      Feature definitions
      *)
  
negative.code:                         if title.Contains word then acc + weight else acc) 0.
                  score
  
      let ``matching voltage`` : FeatureLearner = 
          fun sample ->
              fun obs -> 
                  match (findMeasure pVolts obs.SearchTerm) with
                  | None -> 0.
                  | Some(v) ->
                      match (findMeasure pVolts obs.Product.Title) with
                      | None -> -1.0
                      | Some(r) -> closeness 0.5 v r
  
      let ``matching wattage`` : FeatureLearner = 
          fun sample ->
              fun obs -> 
                  match (findMeasure pWatts obs.SearchTerm) with
                  | None -> 0.
                  | Some(v) ->
                      match (findMeasure pVolts obs.Product.Title) with
                      | None -> -1.0
                      | Some(r) -> closeness 0.5 v r
  