Updated problem_06 in Project Euler (#2439)

* * rename variable
* fix type hint
* fix doctest

* added test function

* fixed import error

* fixup! Format Python code with psf/black push

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>

Du Yuanchao committed 5y ago

2de2267319c2c44e416b840daa370ef463d655fe

Parent: 86fb299

Committed by GitHub <noreply@github.com> on 9/17/2020, 9:37:53 AM