text: """Circle invitation managers"""
  
  #Django
  from django.db import models
  
  #Utilities
  import random
  from string import ascii_uppercase, digits
  
  class InvitationManager(models.Manager):
      """Invitation manager
      Used to handle code creation
      """
      CODE_LENGTH = 10
      def create(self, **kwargs):
          """Handle code creation."""
          pool = ascii_uppercase + digits + '.-'
          code = kwargs.get('code', ''.join(random.choices(pool, k=self.CODE_LENGTH)))
          while self.filter(code=code).exists():
              code = ''.join(random.choices(pool, k=self.CODE_LENGTH))
          kwargs['code'] = code
          return super(InvitationManager, self).create(**kwargs)