code: protected void createDtdSchema(final LmlParser parser, final Appendable appendable) throws Exception {
          Dtd.saveSchema(parser, appendable);
      }
docs: This is a utility method that allows you to hook up into DTD generation process or even modify it completely.
  This method is called by {@link #saveDtdSchema(FileHandle)} after the parser was already set to non-strict. By
  default, this method calls standard DTD utility method: {@link Dtd#saveSchema(LmlParser, Appendable)}. By
  overriding this method, you can generate minified schema with
  {@link Dtd#saveMinifiedSchema(LmlParser, Appendable)} or manually append some customized tags and attributes
  using {@link Appendable} API.
  
  <p>
  If you want to generate DTD schema file for your LML parser, use {@link #saveDtdSchema(FileHandle)} method
  instead.
  
  @param parser its schema will be generated.
  @param appendable a reference to target file.
  @see #saveDtdSchema(FileHandle)
  @throws Exception if your saving method throws any exception, it will wrapped with {@link GdxRuntimeException}
  and rethrown.