Add simple case: 1 returns [1]
Build up an initial set of tests
Add Generator.generate
Add Generator.generate_all
Add Generator.generations
Add Generator.find
Implement Power.find(n)
Retire Generator.generations
Add Generator.find_all
Extract method Generator.generate_new_numbers
Add Array#set_add so that we don't need Set
Refactor Generator.generate and supporting methods
Refactor: rename Generator.generate to .generate_next_power_sets
Refactor: rename methods Generator.generate_power_set(s) build_power_set(s)
Refactor: rename method Generator.generate_all to .generate_all_next_power_sets
Refactor: merge Generator into Power
Source code formatting: adjust white space, indentation
Refactor: rename var sets to power_set_collection
Refactor: rename Power.power_set_collection .power_sets
Implement Power.find() using Power.find_all()