using python to post data to a form

[Littlefield, Tyler]

Hello:
I have some data that needs to be fed through a html form to get 
validated and processed and the like. How can I use python to send data 
through that form, given a specific url? the form says it uses post, but 
I"m not really sure what the difference is. would it just be:
http://mysite.com/bla.php?foo=bar&bar=foo?
If so, how do I do that with python?

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Thanks,
Ty