Short solution needed: "Linear regression" (python-scikit-learn)

[nonunicorn]

Please help us write most modern and shortest code solution for this issue: Linear regression (technology: python-scikit-learn)

Fast way

Just write the code solution in the comments.

Prefered way

1. Create pull request with a new code file inside inbox folder.
2. Don't forget to use comments explain solution.
3. Link to this issue in comments of pull request.

[nonunicorn]

Simple linear regression example