typename MathMLBuilderMap::const_iterator m = mathmlMap.find(el.get_localName()); if (m != mathmlMap.end()) return (this->*(m->second))(el); else return 0;
if (el) {  typename MathMLBuilderMap::const_iterator m = mathmlMap.find(el.get_localName()); if (m != mathmlMap.end()) return (this->*(m->second))(el); } return 0;
  getMathMLElementNoCreate(const typename Model::Node& el) const  {    //std::cout << "createMathMLElement " << el.get_localName() << std::endl;    typename MathMLBuilderMap::const_iterator m = mathmlMap.find(el.get_localName());    if (m != mathmlMap.end())       return (this->*(m->second))(el);    else      return 0;  }