'Recursively remove empty/None values.'

def force_clean(self, **kwargs):

    keys = list(self.keys())
    for key in keys:
        try:
            self[key].force_clean()
        except AttributeError:
            pass
        if isinstance(self[key], (dict, list)):
            if (len(self[key]) == 0):
                del self[key]
        elif (self[key] is None):
            del self[key]
