anchor.diff:      
       open System
   
  +    ///Converts integer to hex based character (e.g. 1 -> '1', 11 -> 'B')
       [<CompiledName("ToHexDigit")>]
       let toHexDigit n =
           if n < 10 then char (n + 0x30) else char (n + 0x37)
       
  +    ///Converts a hex based character to an integer (e.g. '1' -> 1, 'B' -> 11)
       [<CompiledName("FromHexDigit")>]
       let fromHexDigit c =
           if c >= '0' && c <= '9' then int c - int '0'
           elif c >= 'A' && c <= 'F' then (int c - int 'A') + 10
           elif c >= 'a' && c <= 'f' then (int c - int 'a') + 10
           else raise <| new ArgumentException()
  -        
  +    
  +    ///Encodes a color byte array to a hex string with the given prefix 
       [<CompiledName("Encode")>]
       let encode (prefix:string) (color:byte array)  =
           let hex = Array.zeroCreate (color.Length * 2)
  
positive.code: 
          // From publication: Escaping RGBland: Selecting Colors for Statistical Graphics
          // http://epub.wu.ac.at/1692/1/document.pdf
          module StatisticalGraphics24 =
          // 
              let Blue1       = fromRgb   2  63 165
  
negative.code:                 byte v
          {A= f a; R = f r; G = f g; B = f b}
  
      /// Creates a Color structure from the specified color component values (red, green, and blue).
      /// The alpha value is implicitly 255 (fully opaque). 
      let fromRgb r g b =
          fromArgb 255 r g b
  