code: public void appendTo(
        Appendable out,
        DependencyInfo info,
        CharSource content) throws IOException {
      if (info.isModule()) {
        mode.appendGoogModule(transpile(content.read()), out, sourceUrl);
      } else if ("es6".equals(info.getLoadFlags().get("module")) && transpiler == Transpiler.NULL) {
        // TODO(johnplaisted): Make the default transpiler the ES_MODULE_TO_CJS_TRANSPILER. Currently
        // some code is passing in unicode identifiers in non-ES6 modules the compiler fails to parse.
        // Once this compiler bug is fixed we can always transpile.
        mode.appendTraditional(transpileEs6Module(content.read()), out, sourceUrl);
      } else {
        mode.appendTraditional(transpile(content.read()), out, sourceUrl);
      }
    }
docs: Append the contents of the CharSource to the supplied appendable.