Keyword arguments:
            namespaceURI -- namespace of attribute
            localName -- local name of attribute

def getAttributeValue(self, namespaceURI, localName):
        '''
        Keyword arguments:
            namespaceURI -- namespace of attribute
            localName -- local name of attribute
        '''
        if self.hasAttribute(namespaceURI, localName):
            attr = self.node.getAttributeNodeNS(namespaceURI,localName)
            return attr.value
        return None