Fix errors found in the input_output notebook (#258)

* Fixing some issues with the input_output notebook
and changing some exercies a bit.

* Added an exercise to input_output notebook

* Added Docstrings to exercises

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Changes for pre-commit

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Variable naming consistent in tests.

* Reformulation program execution

Co-authored-by: Despina Adamopoulou <16343312+despadam@users.noreply.github.com>

* Review from despina fixes

* Resetting inputfiles after exercises (after writing to file is explained)

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* to_bytes function needs byteorder

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Despina Adamopoulou <16343312+despadam@users.noreply.github.com>

Author: 3 people