Update one or more existing table rows.

        :type table: str
        :param table: Name of the table to be modified.

        :type columns: list of str
        :param columns: Name of the table columns to be modified.

        :type values: list of lists
        :param values: Values to be modified.

def update(self, table, columns, values):
        """Update one or more existing table rows.

        :type table: str
        :param table: Name of the table to be modified.

        :type columns: list of str
        :param columns: Name of the table columns to be modified.

        :type values: list of lists
        :param values: Values to be modified.
        """
        self._mutations.append(Mutation(update=_make_write_pb(table, columns, values)))