I understand how to create multisig accounts as specified in the below documentation but am not sure how this works in practice. Suppose I have a partner, we both create a new keypair, and we both need to sign a transaction. The point is that I don't know his keypair and he doesnt know mine.

So how do you setup a process where we both sign a transaction from different computers neither knows the other's keypair info?

<https://spl.solana.com/token>