Add typescript types

[lenovouser]

Closes #8

[lenovouser]

Ping @huan @simonepri

[simonepri]

@lenovouser sorry, this slipped under my radar, thanks for the ping.

[simonepri]

@lenovouser
Can you fix the typing to match these guidelines? (Ignore the one about using tabs and use 2 space indentation instead)
You can find a good example here

Thanks!

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@2c71d95). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master       #9   +/-   ##
=========================================
  Coverage          ?   86.95%           
=========================================
  Files             ?        6           
  Lines             ?      138           
  Branches          ?        0           
=========================================
  Hits              ?      120           
  Misses            ?       18           
  Partials          ?        0

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[lenovouser]

@simonepri no problem. Should be done!

[lenovouser]

@simonepri ping 😃

[lenovouser]

@simonepri I think this is ready to merge 🚀

[soyuka]

tyvm @lenovouser !