How to convert an XML string to a dictionary?

I have a program that reads an XML document from a socket. I have the XML document stored in a string which I would like to convert directly to a Python dictionary, the same way it is done in Django's simplejson library.

Take as an example:

str ="<?xml version="1.0" ?><person><name>john</name><age>20</age></person"
dic_xml = convert_to_dic(str)

Then dic_xml would look like {'person' : { 'name' : 'john', 'age' : 20 } }