old_contents: from django import forms
  from django.utils.translation import pgettext_lazy
  
  from ...product.models import Discount
  
  
  class DiscountForm(forms.ModelForm):
      class Meta:
          model = Discount
          exclude = []
          widgets = {
              'type': forms.RadioSelect()}
  
      def clean(self):
          cleaned_data = super(DiscountForm, self).clean()
          discount_type = cleaned_data['type']
          value = cleaned_data['value']
          if discount_type == Discount.PERCENTAGE and value > 100:
              self.add_error('value', pgettext_lazy('discount error',
                                                    'Percentage discount '
                                                    'cannot be higher than 100%'))
          return cleaned_data
  
new_contents: from django import forms
  from django.utils.translation import pgettext_lazy
  
  from ...product.models import Discount
  
  
  class DiscountForm(forms.ModelForm):
      class Meta:
          model = Discount
          exclude = []
          widgets = {
              'type': forms.RadioSelect()}
  
      def clean(self):
          cleaned_data = super(DiscountForm, self).clean()
          discount_type = cleaned_data['type']
          value = cleaned_data['value']
          if discount_type == Discount.PERCENTAGE and value > 100:
              self.add_error('value', pgettext_lazy(
                  'discount error',
                  'Discount cannot exceed 100%'))
          return cleaned_data
  
subject: Reformat error message