Update battery capacity stats using the input method.

def update(self):
        """Update battery capacity stats using the input method."""
        # Init new stats
        stats = self.get_init_value()

        if self.input_method == 'local':
            # Update stats
            self.glancesgrabbat.update()
            stats = self.glancesgrabbat.get()

        elif self.input_method == 'snmp':
            # Update stats using SNMP
            # Not avalaible
            pass

        # Update the stats
        self.stats = stats

        return self.stats