This function processes a list of possible IDs by removing any NULL entries,
storing a set of checked variables as an attribute and in the specified environment,
and then returning the updated list of possible IDs.
store_checked_ids(checked_ids, possible_ids, env = .joynenv)A list of possible IDs with NULL values removed, and the checked_ids stored as an attribute.
A vector of variable names that have been checked as possible IDs.
A list containing potential identifiers. This list may contain NULL values, which will be removed by the function.
An environment where the checked_ids will be stored. The default is .joynenv.