"""Optimizer for DB"""

class OptimizerDB:
    def __init__(self):
        self.db = {}

    def set(self, key, value):
        self.db[key] = value

    def get(self, key):
        return self.db.get(key)

    def delete(self, key):
        if key in self.db:
            del self.db[key]

    def keys(self):
        return list(self.db.keys())

    def values(self):
        return list(self.db.values())

    def items(self):
        return list(self.db.items())

    def contains(self