code: private void writeAttributes(Element element, Iterable<Attr> attributes) throws IOException {
  		for (Attr attr : attributes) {
  			final String attrName = attr.getName();
  			if (!enableOperatorsSerialization && Opcode.fromAttrName(attrName) != Opcode.NONE) {
  				// skip operator attributes if operators serialization is disabled
  				continue;
  			}
  			final String attrValue = attr.getValue();
  			if (attrValue.isEmpty()) {
  				// do not write the attribute if its value is empty
  				continue;
  			}
  			if (attrValue.equals(HTML.DEFAULT_ATTRS.get(attrName))) {
  				// do not write the attribute if it is a default one with a default value
  				continue;
  			}
  			writeAttribute(attrName, attrValue);
  		}
  	}
docs: Traverse all element's attributes and delegates {@link #writeAttribute(String, String)}. Skip operators if
  {@link #enableOperatorsSerialization} is false. This method is called after element start tag was opened.
  
  @param element element whose attributes to write.
  @throws IOException if underlying writer fails to write.