Tests and updates for packages/data/load.py

[JMP-MO]

Added a tests file for the data.load.py file.

During testing I found the original file doesn't raise errors when passing incorrect data types so I added an error check for this.
I also added comments to the original code file as these helped me test its functionality and understand the purpose of the code and I thought they would be useful for others. I also reformated the list indexing syntax to be more conventional.

All tests were passing and I tested by running some of the tutorial notebooks to check for changes in behaviour.

[coveralls]

Pull Request Test Coverage Report for Build 14491017447

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
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• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 43 of 43 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.2%) to 58.804%

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Totals
Change from base Build 14490112527:	0.2%
Covered Lines:	7918
Relevant Lines:	13096

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💛 - Coveralls