old_contents: from django.db import models
  from django.utils.translation import ugettext as _
  
  from egielda import settings
  
  
  class BookType(models.Model):
      publisher = models.CharField(max_length=150)
      title = models.CharField(max_length=150)
      price = models.IntegerField()
  
      def price_string(self):
          return "%(price).2f%(currency)s" % {'price': (self.price / 100),
                                              'currency': getattr(settings, 'CURRENCY', 'USD')}
  
      def __str__(self):
          return _(
              "%(publisher)s %(title)s, Edition %(edition)d %(publication_year)d" % {
                  'publisher': self.publisher,
                  'title': self.title, 'edition': self.edition,
                  'publication_year': self.publication_year})
new_contents: from django.db import models
  from django.utils.translation import ugettext as _
  
  from egielda import settings
  
  
  class BookType(models.Model):
      publisher = models.CharField(max_length=150)
      title = models.CharField(max_length=150)
      price = models.IntegerField()
  
      def price_string(self):
          return "%(price).2f%(currency)s" % {'price': (self.price / 100),
                                              'currency': getattr(settings, 'CURRENCY', 'USD')}
  
      def __str__(self):
          return _(
              "%(publisher)s %(title)s" % {
                  'publisher': self.publisher,
                  'title': self.title})
subject: Fix __str__ method for BookType Model