Updates the value of a cell.

        :param label: Cell label in A1 notation.
                      Letter case is ignored.
        :type label: str
        :param value: New value.

        Example::

            worksheet.update_acell('A1', '42')

def update_acell(self, label, value):
        """Updates the value of a cell.

        :param label: Cell label in A1 notation.
                      Letter case is ignored.
        :type label: str
        :param value: New value.

        Example::

            worksheet.update_acell('A1', '42')

        """
        return self.update_cell(*(a1_to_rowcol(label)), value=value)