code: def includeme(config):
      
      from .models import (
          AuthUserMixin,
          random_uuid,
          lower_strip,
          encrypt_password,
      )
      add_proc = config.add_field_processors
      add_proc(
          [random_uuid, lower_strip],
          model=AuthUserMixin, field='username')
      add_proc([lower_strip], model=AuthUserMixin, field='email')
      add_proc([encrypt_password], model=AuthUserMixin, field='password')
docs: Set up event subscribers.