def get_keys(self):
        keys = []
        for base_class, sub_class in self.get_valid_classes():
            keys += self._content[base_class][sub_class].keys()
        return keys
Get a list of all the meta data keys that are available.
dataset/ETHPy150Open moloney/dcmstack/src/dcmstack/dcmmeta.py/DcmMetaExtension.get_keys