Add type hint Optional

[jwhonce]

• Add type hint Optional to the ETAPI methods
• Let black abuse the client.py file

[jwhonce]

Some questions: 1) Is tox configured to "work"? I get errors

py36: commands[0]> check-manifest --ignore 'tox.ini,tests/**'
lists of files in version control and sdist do not match!
missing from VCS:
  MANIFEST.in
no MANIFEST.in found
py36: exit 1 (9.82 seconds) /home/jhonce/Projects/Python/trilium-py> check-manifest --ignore 'tox.ini,tests/**' pid=417968
py36: FAIL ✖ in 12.64 seconds

2) Do you have a strong opinion on Black's formatting changes? If so, please let me know and I will add a configuration to tone it down as needed. 3) I am unfamiliar with from sample.simple import add_one, what package would I need to install to pick that up? Or is this a placeholder for something else.

[Nriver]

1. I think that file comes from certain python package template project. I never used it.
2. The formatting looks good. But I prefer to use single quote over double quotes. I am unfamiliar with Black, is it possible to make it to single quote?
3. It's the same as 1.

[jwhonce]

@Nriver I setup pyproject.toml to leave the quotes alone.

[Nriver]

Thank you!