How to : Python UDF dictionary return schema in PIG

What is the output schema to return a dictionary from Python UDF while using Apache PIG.

I have a dictionary of dictionaries, something like this:

dict = {x:{a:1,b:2,c:3}, y:{d:1,e:3,f:9}}

and my output schema looks like

@outputSchema("m:map[im:map[X:float,Y:float]]") 

** square brackets because in Pig we use [] for map which this dictionary is converted to.