tramp-default-proxies-alist help

[Ned Ludd]

I'm a bit confused about the format of the "tramp-default-proxies-alist".

Here's what I want to do: 

I need to be able to do multi-multi-hop connections. In other words to connect to host4 I need to connect first to host1 (bastion), then from there to host2, then to host3, then to host4:

me --> host1 --> host2 --> host3 --> host4

Assuming I connect to all of these with "ssh" ("setq tramp-default-method ssh"), how do I concoct my "tramp-default-proxies-alist"?

I have the following, but it does not seem to work: it connects to host1, and then tries to jump directly to host4:

(add-to-list 'tramp-default-proxies-alist '("\\." nil "/ssh:host1:"))
(add-to-list 'tramp-default-proxies-alist '("host2'" nil "/ssh:host1:"))
(add-to-list 'tramp-default-proxies-alist '("host3'" nil "/ssh:host2:"))
(add-to-list 'tramp-default-proxies-alist '("host4'" nil "/ssh:
address@hidden:"))

Can you help?
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Ned Ludd