code: public Sections sections(String type) {
          Sections result = sectionsByType.get(type);
          if (result == null) {
              result = new Sections();
              sectionsByType.put(type,  result);
          }
          return result;
      }
docs: Get all of the sections of a particular type.
  
  @param type section type
  @return list of sections of the requested type, or <code>null</code> if there are no sections of that type