Adding some types hints.

[gabrieldemarmiesse]

See the PR keras-team/keras-tuner#163 . If we don't need to support python 2, this should be fine to do it. The types are already displayed in the function signature in the docs, but I plan to also add them in the text description automatically with keras-autodoc. Here is what it looks like right now:

[haifeng-jin]

Here is an overview of what got changed by this pull request:

Issues
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- Added 1
           

See the complete overview on Codacy

[gabrieldemarmiesse]

@haifeng-jin I believe that adding type hints is a safe move. It doesn't have any runtime consequences. From the pep:

While these annotations are available at runtime through the usual __annotations__ attribute, no type checking happens at runtime.

Adding some tool on top of it might. But this PR is focused only on type hints.

I believe it is safe to merge an doesn't necessitate a review from @fchollet or @omalleyt12 .

[haifeng-jin]

@gabrieldemarmiesse
I think it is a good idea to do so if it can save the manual type check and error raising process.
However, since I am really not familiar with this mechanism there might be some cons we are not aware of. Adding it to all APIs would have some workload.
I would rather wait for the reviews from @fchollet and @omalleyt12 before we proceed.
Thank you for your patience.

[gabrieldemarmiesse]

Ok, it doesn't hurt to have another opinion :)

[gabrieldemarmiesse]

Also if we decide to type the API surface and do runtime type checks, I'd be happy to implement it :)

[fchollet]

However, since I am really not familiar with this mechanism there might be some cons we are not aware of.

What are some potential issues?

[haifeng-jin]

However, since I am really not familiar with this mechanism there might be some cons we are not aware of.

What are some potential issues?

I don't know.
If you don't see any potential issue, then we can just do it.

[haifeng-jin]

I am merging it. It would be great if you can continue to work on adding type hints to other classes in task.py and auto_model.py. Thank you! @gabrieldemarmiesse