python: ot_precondition.py add missing import
python: ot_precondition.py add missing import

electronic-structure/sirius,toxa81/sirius,electronic-structure/sirius,toxa81/sirius,electronic-structure/sirius,electronic-structure/sirius,toxa81/sirius,toxa81/sirius,electronic-structure/sirius,electronic-structure/sirius,electronic-structure/sirius,toxa81/sirius,toxa81/sirius