e.g.
It's easy to access github private resources later through specific header settings.

cask 'XXXX' do
...
  url "https://raw.githubusercontent.com/....",
      header: "Authorization: token #{ENV['HOMEBREW_GITHUB_API_TOKEN']}"
...
end

Write the following code, such as ~/.bashrc, ~/.zshrc, etc.

export HOMEBREW_GITHUB_API_TOKEN=<personal access token>

<personal access token>: A personal access token for the GitHub API, requires
repo access permission (full control of private repositories).

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew style with your changes locally?
• Have you successfully run brew tests with your changes locally?