<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def getAttributeNode(self, attr: str) -> Optional[Attr]: """Get attribute of this node as Attr format. If this node does not have ``attr``, return None. """

        return self.attributes.getNamedItem(attr)