Hard code iteration = "list"

[Aariq]

Closes #81 by hard-coding iteration = "list" for all tar_ functions.

Feedback requested:

• Where to set iteration = "list"---in the defaults for tar_stars(), the call to tar_stars_raw(), the defaults for tar_stars_raw(), or in the call to targets::tar_target_raw()?
• Should I add a note somewhere in documentation explaining why iteration has to be "list"?

[njtierney]

Looks good to me!

[njtierney]

RE:

Feedback requested:

• Where to set iteration = "list"---in the defaults for tar_stars(), the call to tar_stars_raw(), the defaults for tar_stars_raw(), or in the call to targets::tar_target_raw()?

So I think it would make sense to have this hard coded as the default - so put it inside of tar_stars_raw().

• Should I add a note somewhere in documentation explaining why iteration has to be "list"?

This would be great - either as a #' @note or #' @description. We can also log this as an issue to revisit down the track?