# File lib/travis/tools/github.rb, line 59
      def possible_tokens(&block)
        return block[github_token] if github_token

        if auto_token
          netrc_tokens(&block)
          git_tokens(&block)
          hub_tokens(&block)
          oauth_file_tokens(&block)
          github_for_mac_token(&block)
          issuepost_token(&block)
          composer_token(&block)
        end

        if auto_password
          possible_logins do |user, password|
            yield login(user, password, false)
          end
        end

        if manual_login
          user, password = ask_credentials
          yield login(user, password, true)
        end

        after_tokens.call
      end