docs: public static void main(String[] args) throws IOException {
      if (args.length != 0) {
        System.err.println("Reads from STDIN and writes to STDOUT");
        System.exit(-1);
      }
      System.err.println("[Reading from STDIN]");
      // Fetch the HTML to sanitize.
      String html = CharStreams.toString(
          new InputStreamReader(System.in, Charsets.UTF_8));
      // Set up an output channel to receive the sanitized HTML.
      HtmlStreamRenderer renderer = HtmlStreamRenderer.create(
          System.out,
          // Receives notifications on a failure to write to the output.
          new Handler<IOException>() {
            public void handle(IOException ex) {
              // System.out suppresses IOExceptions
              throw new AssertionError(null, ex);
            }
          },
          // Our HTML parser is very lenient, but this receives notifications on
          // truly bizarre inputs.
          new Handler<String>() {
            public void handle(String x) {
              throw new AssertionError(x);
            }
          });
      // Use the policy defined above to sanitize the HTML.
      HtmlSanitizer.sanitize(html, POLICY_DEFINITION.apply(renderer));
    }