docs: private static Node serializeEntry(Entry e, DocumentFactory fac) {
  
          // Assertions...
          if (e == null) {
              String msg = "Argument 'e [Entry]' cannot be null.";
              throw new IllegalArgumentException(msg);
          }
          if (fac == null) {
              String msg = "Argument 'fac' cannot be null.";
              throw new IllegalArgumentException(msg);
          }
  
          Element rslt = fac.createElement("entry");
          rslt.addAttribute("type", e.getType().name());
  
          // Name.
          Element name = fac.createElement("name");
          name.setText(e.getName());
          rslt.add(name);
  
          // Deprecation.
          if (e.isDeprecated()) {
              Element dep = fac.createElement("deprecation");
              dep.addAttribute("version", e.getDeprecation().getVersion());
              for (Element n : e.getDeprecation().getDescription()) {
              	dep.add((Element) n.clone());
              }
              rslt.add(dep);
          }
  
          // Description.
          Element desc = e.getDescription() != null 
          				? (Element) e.getDescription().clone() 
          				: fac.createElement("description");
          rslt.add(desc);
  
          // Formula.
          rslt.add(serializeFormula(e.getFormula(), e.getMappings(), fac));
  
          // Examples.
          for (Node x : e.getExamples()) {
              rslt.add((Node) x.clone());
          }
  
          return rslt;
  
      }