def __str__(self):
        res = '\n----- WORLD SUMMARY for : ' + self.nme + ' -----\n'
        res += 'population = ' + str( self.population) + '\n'
        res += 'tax_rate   = ' + str( self.tax_rate) + '\n'
        res += 'tradition  = ' + str( self.tradition) + '\n'