function entryPoint(entry) {
  return (context, util) =>
    util.merge({
      entry: normalizeEntry(entry)
    })
}
Adds one or multiple entry points. If the parameter is not an object the
entry point(s) will be added to the default chunk named `main`.

@param {object|string[]|string} entry
@see https://webpack.github.io/docs/configuration.html#entry