This function returns the primary user that the input recipe ID can be
linked to. It can be used to determine which primary account the linking
will happen to if the input recipe user ID was to be linked.
If the function returns undefined, it means that there is no primary user
that the input recipe ID can be linked to, and therefore it can be made
into a primary user itself.
This function returns the primary user that the input recipe ID can be linked to. It can be used to determine which primary account the linking will happen to if the input recipe user ID was to be linked.
If the function returns undefined, it means that there is no primary user that the input recipe ID can be linked to, and therefore it can be made into a primary user itself.