anchor.diff:              dictionary
           else
               // TODO : Add an error message which includes the key.
  +            //keyNotFound ""
               raise <| System.Collections.Generic.KeyNotFoundException ()
   
       /// Updates the value of an entry (which has the specified key) in
  
positive.code:     /// Removes the entry with the specified key from the Dictionary.
      /// An exception is raised if the entry cannot be removed.
      let [<NoDynamicInvocation>] inline remove (k : 'Key) (dictionary : IDictionary<'Key, 'T>) =
          if dictionary.Remove k then dictionary
          else failwithf "Unable to remove the entry with the key '%O' from the dictionary." k
  
      /// Lookup an element in the Dictionary, raising KeyNotFoundException if
      /// the dictionary does not contain an element with the specified key.
  
negative.code:                 if d.ContainsKey k then
                      d.[k] <- v
                  else
                      // TODO : Return a better error message
                      //keyNotFound ""
                      raise <| System.Collections.Generic.KeyNotFoundException ()
  
          /// Removes the entry with the specified key from the Dictionary,
  