python retrieve xml acting like a web browser [duplicate]

This question already has an answer here:

• Changing user agent on urllib2.urlopen 6 answers

I want to make a url request to get an xml page using python.

When i use the

urllib2.Request(myurl)

I got 403 forbidden

When i use

webbrowser.open(myurl)

I can open the url in my browser.

I have learned from a java coder that he used the code below in java to make the program look like a browser so the program could retrieve the xml file without being blocked by the server.

resource.getClientInfo().setAgent("Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:25.0) Gecko/20100101 Firefox/25.0");

I am wondering if python can do something similar and if so where can I find the resources.