* added mean absolute error to loss_functions.py
* added doctest to mean absolute error to loss_functions.py
* fixed long line in loss_functions.py
* [pre-commit.ci] auto fixes from pre-commit.com hooks
for more information, see https://pre-commit.ci
* fixed error in MAE
* Update machine_learning/loss_functions.py
Co-authored-by: Tianyi Zheng <tianyizheng02@gmail.com>
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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Tianyi Zheng <tianyizheng02@gmail.com>