The output of help(open) (and `pydoc open`) in 3.4 is:
Help on built-in function open in module io:
open(...)
errors=None, newline=None, closefd=True, opener=None) -> file object
Open file and return a stream. Raise IOError upon failure.
...
In 3.3 and older it works correctly:
Help on built-in function open in module io:
open(...)
open(file, mode='r', buffering=-1, encoding=None,
errors=None, newline=None, closefd=True, opener=None) -> file object
Open file and return a stream. Raise IOError upon failure.
...