This name is a little weird, and has stutter for users: `hkclient.HkClients(…)`.
Consider `New` or `Open` or something if you can find an appropriate one.
An plain verb like would be good if `Clients` is the primary type of this package,
which it seems to be.

Same goes for `HkNetRc` and any other prefixed exported symbols.
I'd suggest `Netrc` (or `NetRc` if you prefer that capitalization) instead.