not sure what's different here
test for school_k._prep_k_data written and passing
fixed indexing bug in closest_schools._pick_n if repetitive distances were at end of distance list
closest_schools._pick_n tests written and pass
first test for find_n_closest_schools written and passes
test written and passes for a limited example.  Correct answers calculated in xlsx spreadsheet.
testing finished and passing on closest_schools modulegit add .! some more Excel spreadsheets of correct answers added.
tiny bit of code cleanup