To release a new version of ipyevents on PyPI:

Update _version.py (set release version, remove 'dev'), package.json and src/version.ts
git add the _version.py file and git commit
python setup.py sdist
python setup.py bdist_wheel
twine upload dist/ipyevents*
git tag -a X.X.X -m 'comment'
Update _version.py (add 'dev' and increment minor)
git add and git commit
git push
git push --tags

To release a new version of ipyevents on NPM:

# clean out the `dist` and `node_modules` directories
git clean -fdx
npm install
npm run build
npm publish