*.py: Stylistic adjustments for python (#8233)

* Superflous parens in conditionals were removed.
* Unused args in function were removed.
* Replaced unused `idx` var with `_`
* Initializing file_format and format_version attributes
* Renaming constant to capitals
* Preventing redefinition of the `f` var

Signed-off-by: Jiri Podivin <jpodivin@redhat.com>