+ ##
+ # Look up user records given PLC user-ids. This is used as part of the
+ # process for reverse-mapping PLC records into Geni records.
+ #
+ # @param auth_table database table for the authority that holds the user records
+ # @param user_id_list list of user ids
+ # @param role either "*" or a string describing the role to look for ("pi", "user", ...)
+ #
+ # TODO: This function currently only searches one authority because it would
+ # be inefficient to brute-force search all authorities for a user id. The
+ # solution would likely be to implement a reverse mapping of user-id to
+ # (type, hrn) pairs.
+