def add_key(self, key, first=False):
if first:<EOL><INDENT>self.keys = [key] + self.keys<EOL><DEDENT>else:<EOL><INDENT>self.keys.append(key)<EOL><DEDENT>if isinstance(key, VSpaceKey):<EOL><INDENT>self.space = key<EOL><DEDENT>
Adds the given key to this row.

        :param key: Key to be added to this row.
        :param first: BOolean flag that indicates if key is added at the beginning or at the end.