def get_option_default(self, key, subkey):
key, subkey = _lower_keys(key, subkey)<EOL>_entry_must_exist(self.gc, key, subkey)<EOL>df = self.gc[(self.gc["<STR_LIT>"] == key) & (self.gc["<STR_LIT>"] == subkey)]<EOL>if df["<STR_LIT:type>"].values[<NUM_LIT:0>] == "<STR_LIT:bool>":<EOL><INDENT>return bool(df["<STR_LIT:default>"].values[<NUM_LIT:0>])<EOL><DEDENT>elif df["<STR_LIT:type>"].values[<NUM_LIT:0>] == "<STR_LIT:int>":<EOL><INDENT>return int(df["<STR_LIT:default>"].values[<NUM_LIT:0>])<EOL><DEDENT>else:<EOL><INDENT>return df["<STR_LIT:default>"].values[<NUM_LIT:0>]<EOL><DEDENT>
Get the default value of the option.

        :param str key: First identifier of the option.
        :param str subkey: Second identifier of the option.

        :return: Default value of the option (type varies).

        :raise:
            :NotRegisteredError: If ``key`` or ``subkey`` do not define
                any option.