Return element in xml files which match with the tag name and the specific attribute

            :param tag_name: specify the tag name
            :type tag_name: string
            :param attribute: specify the attribute
            :type attribute: string

            :rtype: string

def get_element(self, tag_name, attribute, **attribute_filter):
        """
            Return element in xml files which match with the tag name and the specific attribute

            :param tag_name: specify the tag name
            :type tag_name: string
            :param attribute: specify the attribute
            :type attribute: string

            :rtype: string
        """
        for i in self.xml:
            if self.xml[i] is None :
                continue
            tag = self.xml[i].getElementsByTagName(tag_name)
            if tag is None:
                return None
            for item in tag:
                skip_this_item = False
                for attr, val in list(attribute_filter.items()):
                    attr_val = item.getAttributeNS(NS_ANDROID_URI, attr)
                    if attr_val != val:
                        skip_this_item = True
                        break

                if skip_this_item:
                    continue

                value = item.getAttributeNS(NS_ANDROID_URI, attribute)

                if len(value) > 0:
                    return value
        return None