Teach flywire_ids to accept file argument

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 56.64%. Comparing base (e8ad468) to head (b47b975). Report is 1 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #199 +/- ## ========================================== + Coverage 56.59% 56.64% +0.05% ========================================== Files 38 38 Lines 4787 4793 +6 ========================================== + Hits 2709 2715 +6 Misses 2078 2078 ```

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