old_contents: """Django DDP app config."""
  
  from __future__ import print_function
  
  from django.apps import AppConfig
  from django.conf import settings, ImproperlyConfigured
  from django.db import DatabaseError
  from django.db.models import signals
  
  from dddp import autodiscover
  from dddp.models import Connection
  
  
  class DjangoDDPConfig(AppConfig):
  
      """Django app config for django-ddp."""
  
      api = None
      name = 'dddp'
      verbose_name = 'Django DDP'
      _in_migration = False
  
      def ready(self):
          """Initialisation for django-ddp (setup lookups and signal handlers)."""
          if not settings.DATABASES:
              raise ImproperlyConfigured('No databases configured.')
          for (alias, conf) in settings.DATABASES.items():
              if conf['ENGINE'] != 'django.db.backends.postgresql_psycopg2':
                  raise ImproperlyConfigured(
                      '%r uses %r: django-ddp only works with PostgreSQL.' % (
                          alias, conf['backend'],
                      )
                  )
          self.api = autodiscover()
          self.api.ready()
  
new_contents: """Django DDP app config."""
  
  from __future__ import print_function
  
  from django.apps import AppConfig
  from django.conf import settings, ImproperlyConfigured
  
  from dddp import autodiscover
  
  
  class DjangoDDPConfig(AppConfig):
  
      """Django app config for django-ddp."""
  
      api = None
      name = 'dddp'
      verbose_name = 'Django DDP'
      _in_migration = False
  
      def ready(self):
          """Initialisation for django-ddp (setup lookups and signal handlers)."""
          if not settings.DATABASES:
              raise ImproperlyConfigured('No databases configured.')
          for (alias, conf) in settings.DATABASES.items():
              if conf['ENGINE'] != 'django.db.backends.postgresql_psycopg2':
                  raise ImproperlyConfigured(
                      '%r uses %r: django-ddp only works with PostgreSQL.' % (
                          alias, conf['backend'],
                      )
                  )
          self.api = autodiscover()
          self.api.ready()
  
subject: Remove unused imports from AppConfig module.