é o arquivo uma chave em python

#No, file is a builtin, not a keyword:
>>> import keyword
>>> keyword.iskeyword('file')
False
>>> import __builtin__
>>> hasattr(__builtin__, 'file')
True
It can be seen as an alias for open(), 
but it has been removed from Python 3, 
as the new io framework replaced it. 
Technically, it is the type of object returned by the open() function.
Real Raccoon