simplexml: consistent interface for xml attributes -- __contains__

src/common/xmpp/simplexml.py

@@ -253,6 +253,9 @@ class Node(object):
 	def __delitem__(self,item):
 		""" Deletes node's attribute "item". """
 		return self.delAttr(item)
+	def __contains__(self,item):
+		""" Checks if node has attribute "item" """
+		self.has_attr(item)
 	def __getattr__(self,attr):
 		""" Reduce memory usage caused by T/NT classes - use memory only when needed. """
 		if attr=='T':