A line like

```
print("foo", end=" ")
```

is reported as `E901 SyntaxError: invalid syntax` invalid syntax by `flake8`.


----
`pep8` doesn't complain but `flake8` does even though `flake8` uses `pep8`.

I wonder if that means the problem is with `pyflakes` (which `flake8` also uses).

----
Note that the line *is* a `SyntaxError` in Python 2.

----
`python3 -m flake8 test.py`

works whereas

`python2 -m flake8 test.py`

doesn't. So the problem just seems to be that the `flake8` I'm running on command line (and in Atom Editor) is hard-coded to be the Python 2 one.


----
`pyflakes` gives the error, so `flake8` is almost certainly getting it from there not `pep8`.

----
Maybe the solution is to get rid of `pyflakes` (and the rest of `flake8`) from the global site-packages.

----
It appears Atom Editor will use the right Python version to run `flake8` if it is started up in the virtualenv (otherwise, after you remove `flake8` from the global site-packages, Atom will complain that `flake8` doesn't exist.

----
One thing I haven't tested yet is starting up two Atom windows, one from a Python 2 virtualenv and one from a Python 3 virtualenv.


----
Okay, so I've tested that now. It appears multiple Atom windows will use the `flake8` in the virtualenv where Atom was *first* started up.

It also means that if you start up Atom from somewhere other than `atom` on the command line (in a virtualenv) `flake8` won't be available.

----
In summary, if you develop with both Python 2 and Python 3 and want to use `flake8`:

* don't install `flake8` at global site-packages level
* always use virtual environments
* if you use Atom Editor with `flake8` support, always start up `atom` from within the virtual environment