Python operating on files in a folder - 'for file in folder'
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I know a folder's path, and for every file in the folder I would like to do some operations. So essentially what I'm looking for is a `for file in folder` type of code that gives me access to the files in variables. 

What is the Python way of doing this? 

Thanks

EDIT - example: my folder will contain a bunch of XML files, and I have a python routine already to parse them into variables I need. 