code: public String text() {
          String previousText = null;
          StringBuilder buffer = null;
          for (Object child : this) {
              String text = null;
              if (child instanceof String) {
                  text = (String) child;
              } else if (child instanceof Node) {
                  text = ((Node) child).text();
              }
              if (text != null) {
                  if (previousText == null) {
                      previousText = text;
                  } else {
                      if (buffer == null) {
                          buffer = new StringBuilder();
                          buffer.append(previousText);
                      }
                      buffer.append(text);
                  }
              }
          }
          if (buffer != null) {
              return buffer.toString();
          }
          if (previousText != null) {
              return previousText;
          }
          return "";
      }
docs: Returns the text value of all of the elements in the collection.
  
  @return the text value of all the elements in the collection or null