uuid.py

class Document(models.Model)
   def get_uuid(self):
        def bijective_encode(i, start=0):
            #http://stackoverflow.com/a/742047/754305
            i += start
            CHARS = list('zpYUgh9XWvHbNVK6kmAufqCSeyiBZ7RcLd4GJ5ETMnwPDrx3s8QaF2jt') #randomized to avoid iteration
            s = ''
            base = len(CHARS)
            while i > 0:
                s += CHARS[i % base]
                i /= base
            return s[::-1]

        return bijective_encode(self.id, start=int(1e5))