# File lib/googleauth/credentials.rb, line 87
      def self.default options = {}
        # First try to find keyfile file from environment variables.
        client = from_path_vars options

        # Second try to find keyfile json from environment variables.
        client ||= from_json_vars options

        # Third try to find keyfile file from known file paths.
        client ||= from_default_paths options

        # Finally get instantiated client from Google::Auth
        client ||= from_application_default options
        client
      end