code: def omitted_predictions(self):
          
          if self.__omitted_predictions is None:
              self.log("loading omitted_predictions")
              self.__load_omitted_predictions()
              self.log("loading omitted_predictions")
          return self.__omitted_predictions
docs: get the omitted prediction sensitivity vectors (stored as
          a pyemu.Matrix)
  
          Returns
          -------
          omitted_predictions : pyemu.Matrix
              a matrix of prediction sensitivity vectors (column wise) to
              omitted parameters
  
          Note
          ----
          returns a reference
          
          if ErrorVariance.__omitted_predictions is not set, then dynamically load the
          attribute before returning