ThrottlingException leads to "Unknown error"

[a1exsh]

I was running piu a number of times sequentially to jump to many hosts. Out of 22 runs 3 resulted Unknown Error. printed on console and a traceback logged, like this one:

Traceback (most recent call last):
  File "/home/oshulgin/.local/lib/python3.6/site-packages/piu/error_handling.py", line 33, in wrapper
    func()
  File "/home/oshulgin/.local/lib/python3.6/site-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "/home/oshulgin/.local/lib/python3.6/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/home/oshulgin/.local/lib/python3.6/site-packages/click/core.py", line 1259, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/home/oshulgin/.local/lib/python3.6/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/oshulgin/.local/lib/python3.6/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/home/oshulgin/.local/lib/python3.6/site-packages/click/decorators.py", line 33, in new_func
    return f(get_current_context().obj, *args, **kwargs)
  File "/home/oshulgin/.local/lib/python3.6/site-packages/piu/cli.py", line 388, in request_access
    if not send_odd_ssh_key(ec2, first_host, ssh_public_key):
  File "/home/oshulgin/.local/lib/python3.6/site-packages/piu/cli.py", line 424, in send_odd_ssh_key
    return send_ssh_key("odd", odd_attributes, public_key)
  File "/home/oshulgin/.local/lib/python3.6/site-packages/piu/cli.py", line 435, in send_ssh_key
    AvailabilityZone=host["Placement"]["AvailabilityZone"],
  File "/home/oshulgin/.local/lib/python3.6/site-packages/botocore/client.py", line 316, in _api_call
    return self._make_api_call(operation_name, kwargs)
  File "/home/oshulgin/.local/lib/python3.6/site-packages/botocore/client.py", line 626, in _make_api_call
    raise error_class(parsed_response, operation_name)
botocore.errorfactory.ThrottlingException: An error occurred (ThrottlingException) when calling the SendSSHPublicKey operation (reached max retries: 4): Server is busy! Please retry after a moment.

Should I maybe have some sleep in between? ;)