old_contents: import json
  
  from django import forms
  from django.utils import six
  
  from .widgets import JSONWidget
  
  
  class JSONFormField(forms.CharField):
      empty_values = [None, '']
      
      def __init__(self, *args, **kwargs):
          if 'widget' not in kwargs:
              kwargs['widget'] = JSONWidget
          super(JSONFormField, self).__init__(*args, **kwargs)
  
      def to_python(self, value):
          if isinstance(value, six.string_types) and value:
              try:
                  return json.loads(value)
              except Exception as exc:
                  raise forms.ValidationError(
                      'JSON decode error: %s' % (unicode(exc),)
                  )
          else:
              return value
      
      def validate(self, value):
          # This is required in older django versions.
          if value in self.empty_values and self.required:
              raise forms.ValidationError(self.error_messages['required'], code='required')
new_contents: import json
  
  from django import forms
  from django.utils import six
  
  from .widgets import JSONWidget
  
  
  class JSONFormField(forms.CharField):
      empty_values = [None, '']
      
      def __init__(self, *args, **kwargs):
          if 'widget' not in kwargs:
              kwargs['widget'] = JSONWidget
          super(JSONFormField, self).__init__(*args, **kwargs)
  
      def to_python(self, value):
          if isinstance(value, six.string_types) and value:
              try:
                  return json.loads(value)
              except Exception as exc:
                  raise forms.ValidationError(
                      'JSON decode error: %s' % (six.u(exc),)
                  )
          else:
              return value
      
      def validate(self, value):
          # This is required in older django versions.
          if value in self.empty_values and self.required:
              raise forms.ValidationError(self.error_messages['required'], code='required')
subject: Remove use of unicode()