example-ds.py

class DataStore:
    def __init__():
        self.store = {}
        
    def set(key, value):
        self.store[key] = value
    
    def delete(key):
        try:
            del self.store[key]
        except:
            pass
        
    def load(filename):
        raise Exception("Method must be overwritten")
        
    def save(filename):
        raise Exception("Method must be overwritten")
        
class JsonDataStore(DataStore):
    def load(filename):
        # whoo loading stuff yay
        self.store = json.loads(open(filename).read())
        
    def save(filename):
        # whoo saving
        blah blah blah
        
class PickleDataStore(DataStore):
    def load(filename):
        # whoo loading stuff yay
        blah blah
        
    def save(filename):
        # whoo saving
        blah blah blah