Sets a the value in the TOML file located by the given key sequence.

        Example:
        self._setitem(('key1', 'key2', 'key3'), 'text_value')
        is equivalent to doing
        self['key1']['key2']['key3'] = 'text_value'

def _setitem_with_key_seq(self, key_seq, value):
        """
        Sets a the value in the TOML file located by the given key sequence.

        Example:
        self._setitem(('key1', 'key2', 'key3'), 'text_value')
        is equivalent to doing
        self['key1']['key2']['key3'] = 'text_value'
        """
        table = self
        key_so_far = tuple()
        for key in key_seq[:-1]:
            key_so_far += (key,)
            self._make_sure_table_exists(key_so_far)
            table = table[key]
        table[key_seq[-1]] = value