code: function findElementAttributeValue(attributeName, elems) {
  
      elems = Array.isArray(elems) ? elems : [ elems ];
  
      var value = elems.filter(function (elem) {
          return elem.attrib.name.toLowerCase() === attributeName.toLowerCase();
      }).map(function (filteredElems) {
          return filteredElems.attrib.value;
      }).pop();
  
      return value ? value : '';
  }
docs: Finds the value of an element's attribute
  @param  {String} attributeName Name of the attribute to search for
  @param  {Array}  elems         An array of ElementTree nodes
  @return {String}