code: function(content) {
          var node = this.createElementNSPlus("atom:content", {
              attributes: {
                  type: content.type || null
              }
          });
          if (content.src) {
              node.setAttribute("src", content.src);
          } else {
              if (content.type == "text" || content.type == null) {
                  node.appendChild(
                      this.createTextNode(content.value)
                  );
              } else if (content.type == "html") {
                  if (typeof content.value != "string") {
                      throw "HTML content must be in form of an escaped string";
                  }
                  node.appendChild(
                      this.createTextNode(content.value)
                  );
              } else if (content.type == "xhtml") {
                  node.appendChild(content.value);
              } else if (content.type == "xhtml" ||
                             content.type.match(/(\+|\/)xml$/)) {
                  node.appendChild(content.value);
              }
              else { // MUST be a valid Base64 encoding
                  node.appendChild(
                      this.createTextNode(content.value)
                  );
              }
          }
          return node;
      }
docs: Method: buildContentNode
  
  Parameters:
  content - {Object}
  
  Returns:
  {DOMElement} an Atom content node.
  
  TODO: types other than text.