code: def to_native_types(self, slicer=None, na_rep='', quoting=None, **kwargs):
          
  
          values = self.values
          if slicer is not None:
              # Categorical is always one dimension
              values = values[slicer]
          mask = isna(values)
          values = np.array(values, dtype='object')
          values[mask] = na_rep
  
          # we are expected to return a 2-d ndarray
          return values.reshape(1, len(values))
docs: convert to our native types format, slicing if desired