code: public T attr(String name, String value) throws IOException {
  		if (value != null) {
  			writer.write(' ');
  			writer.write(name);
  			writer.write("=\"");
  			writer.write(value);
  			writer.write('\"');
  		}
  		return (T) this;
  	}
docs: Add attribute.
  
  @param name Attribute name
  @param value Attribute value