code: def xform_key(self, key):
          '''we transform cache keys by taking their sha1 hash so that
          we don't need to worry about cache keys containing invalid
          characters'''
  
          newkey = hashlib.sha1(key.encode('utf-8'))
          return newkey.hexdigest(f xform_key(self, key):
          '''we transform cache keys by taking their sha1 hash so that
          we don't need to worry about cache keys containing invalid
          characters'''
  
          newkey = hashlib.sha1(key.encode('utf-8'))
          return newkey.hexdigest()
docs: we transform cache keys by taking their sha1 hash so that
          we don't need to worry about cache keys containing invalid
          characters