Set point size limits of specified subplots.

        :param row_column_list: a list containing (row, column) tuples to
            specify the subplots, or None to indicate *all* subplots.
        :type row_column_list: list or None
        :param min: point size for the lowest value.
        :param max: point size for the highest value.

def set_slimits_for_all(self, row_column_list=None, min=None, max=None):
        """Set point size limits of specified subplots.

        :param row_column_list: a list containing (row, column) tuples to
            specify the subplots, or None to indicate *all* subplots.
        :type row_column_list: list or None
        :param min: point size for the lowest value.
        :param max: point size for the highest value.

        """
        if min is None or max is None:
            raise Exception('Both min and max are required.')
        if row_column_list is None:
            self.limits['smin'] = sqrt(min)
            self.limits['smax'] = sqrt(max)
        else:
            for row, column in row_column_list:
                self.set_slimits(row, column, min, max)