Set ticks for the y-axis.

        :param suffix: string added after each tick. If the value is
                       `degree` or `precent` the corresponding symbols
                       will be added.

def set_ytick_suffix(self, suffix):
        """Set ticks for the y-axis.

        :param suffix: string added after each tick. If the value is
                       `degree` or `precent` the corresponding symbols
                       will be added.

        """
        if suffix == 'degree':
            suffix = r'^\circ'
        elif suffix == 'percent':
            suffix = r'\%'

        self.ticks['ysuffix'] = suffix