def set_start_position(self, percentage_position):
        raise NotImplementedError
Detect dictionary del events and emit change events.
dataset/ETHPy150Open pascalw/Airplayer/airplayer/mediabackends/base_media_backend.py/BaseMediaBackend.set_start_position--crossover with--dataset/ETHPy150Open goFrendiAsgard/kokoropy/kokoropy/packages/sqlalchemy/ext/mutable.py/MutableDict.__delitem__