Remove methods from old approach
Add step to initialization
Add test for candidate array initialization
Implement candidate array initialization
Fix bug in grid_entries method
Add test for missing entries in grid
Implement method for missing entries
Add tests for completed puzzle
Improve completed puzzle method
Add test for candidate entries
Add additional candidate entries test
Update grid, row, and column tests with initialized candidate arrays
Implement initialize candidate entries method
Add test for pruning candidate entries
Add test for pruning error
Implement prune candidates with custom error
Add test for scanning grid to prune candidates
Implement scan grid method
Add test for performing insertions
Implement perform insertions method