TurnHepaOn

class TurnHepaOn(KPFFunction):
    '''Turn HEPA Filter system on

    KTL Keywords Used:

    - `ao.OBHPAON`
    - `ao.OBHPASTA`
    '''
    @classmethod
    def pre_condition(cls, args):
        pass

    @classmethod
    def perform(cls, args):
        OBHPAON = ktl.cache('ao', 'OBHPAON')
        log.debug('Setting AO HEPA filter to off')
        OBHPAON.write(1)

    @classmethod
    def post_condition(cls, args):
        OBHPASTA = ktl.cache('ao', 'OBHPASTA')
        if OBHPASTA.waitfor('== "on"', timeout=3) is not True:
            raise FailedToReachDestination(OBHPASTA.read(), 'on')