NewExpander initializes and returns a new Expander, empty and ready to use.

Expander instances serve as a coordination point for gathering object repetition values (count and for_each in configuration) and then later making use of them to fully enumerate all of the instances of an object.

RepetitionData represents the values available to identify individual repetitions of a particular object.

Set is a set of instances, intended mainly for the return value of Expander.AllInstances, where it therefore represents all of the module and resource instances known to the expander.