Select data at a particular level from a MultiIndex

I have the following Pandas Dataframe with a MultiIndex(Z,A):

             H1       H2  
   Z    A 
0  100  200  0.3112   -0.4197   
1  100  201  0.2967   0.4893    
2  100  202  0.3084   -0.4873   
3  100  203  0.3069   NaN        
4  101  203  -0.4956  NaN       

Question: How can I select all items with A=203? I tried df[:,'A'] but it doesn't work. Then I found this in the online documentation so I tried:
df.xs(203,level='A')
but I get:
"TypeError: xs() got an unexpected keyword argument 'level'"
Also I dont see this parameter in the installed doc(df.xs?):
"Parameters ---------- key : object Some label contained in the index, or partially in a MultiIndex axis : int, default 0 Axis to retrieve cross-section on copy : boolean, default True Whether to make a copy of the data"
Note:I have the development version.

Edit: I found this thread. They recommend something like:

df.select(lambda x: x[1]==200, axis=0)  

I still would like to know what happened with df.xs with the level parameter or what is the recommended way in the current version.