docs: def get_elements(self, tag_name, attribute):
          """
              Return elements in xml files which match with the tag name and the specific attribute
  
              :param tag_name: a string which specify the tag name
              :param attribute: a string which specify the attribute
          """
          l = []
          for i in self.xml:
              for item in self.xml[i].getElementsByTagName(tag_name):
                  value = item.getAttributeNS(NS_ANDROID_URI, attribute)
                  value = self.format_value(value)
  
                  l.append(str(value))
          return l