def __set_formulas(self, formulas):
        """
        Sets formulas in this cell range from an iterable of iterables.

        Any cell values can be set using this method. Actual formulas must
        start with an equal sign.
        """
        # Tuple of tuples is required
        array = tuple(tuple(self._clean_formula(col) for col in row) for row in formulas)
        self._get_target().setFormulaArray(array)