fix new black lint error

[timkpaine]

No description provided.

[codecov-commenter]

Codecov Report

Merging #308 (1b88dfe) into master (2985ff0) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #308   +/-   ##
=======================================
  Coverage   46.24%   46.24%           
=======================================
  Files           4        4           
  Lines        1905     1905           
  Branches      375      375           
=======================================
  Hits          881      881           
  Misses        972      972           
  Partials       52       52           

Impacted Files	Coverage Δ
bt/algos.py	85.74% <ø> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 2985ff0...1b88dfe. Read the comment docs.