def isna(self):
ret = self._codes == -<NUM_LIT:1><EOL>return ret<EOL>
Detect missing values

Missing values (-1 in .codes) are detected.

Returns
-------
a boolean array of whether my values are null

See Also
--------
isna : Top-level isna.
isnull : Alias of isna.
Categorical.notna : Boolean inverse of Categorical.isna.