old_contents: # coding: utf-8
  from django import forms
  from django.conf import settings
  
  
  MOLDER_DEFAULT_CLASSES_FOR_WIDGETS = \
      getattr(settings, 'MOLDER_DEFAULT_CLASSES_FOR_WIDGETS', {
          None: '',  # default
          forms.TextInput: 'form-control',
          forms.ClearableFileInput: 'fileinput',
      })
  
new_contents: # coding: utf-8
  from django import forms
  from django.conf import settings
  
  
  MOLDER_DEFAULT_CLASSES_FOR_WIDGETS = \
      getattr(settings, 'MOLDER_DEFAULT_CLASSES_FOR_WIDGETS', {
          forms.TextInput: 'form-control',
          forms.ClearableFileInput: 'fileinput',
      })
  
  # default class for widgets not listed at `MOLDER_DEFAULT_CLASSES_FOR_WIDGETS`
  MOLDER_DEFAULT_CLASSES_FOR_WIDGETS.setdefault(None, '')
  
subject: Update default config