code: def get_namespaces(start=None, end=None):
    
    q = Namespace.query()
    if start is not None:
      q = q.filter(Namespace.key >= Namespace.key_for_namespace(start))
    if end is not None:
      q = q.filter(Namespace.key < Namespace.key_for_namespace(end))
    return [x.namespace_name for x in q]
docs: Return all namespaces in the specified range.
  
    Args:
      start: only return namespaces >= start if start is not None.
      end: only return namespaces < end if end is not None.
  
    Returns:
      A list of namespace names between the (optional) start and end values.