Syntax error installing gunicorn
Question: I am following this Heroku tutorial:
<https://devcenter.heroku.com/articles/getting-started-with-python-o> and when
I am trying to install gunicorn in a virtualenv I am getting this error:

    
    
    (venv)jabuntu14@ubuntu:~/Desktop/helloflask$ pip install gunicorn
    Downloading/unpacking gunicorn
    Downloading gunicorn-19.1.1-py2.py3-none-any.whl (104kB): 104kB downloaded
    Installing collected packages: gunicorn
    Compiling /home/jabuntu14/Desktop/helloflask/venv/build/gunicorn/gunicorn/workers    /_gaiohttp.py ...
    File "/home/jabuntu14/Desktop/helloflask/venv/build/gunicorn/gunicorn/workers    /_gaiohttp.py", line 64
        yield from self.wsgi.close()
             ^
    
    SyntaxError: invalid syntax
    Successfully installed gunicorn
    Cleaning up...
    

However, when I run $foreman start it appears to work properly.

How important is this error? Any idea how to solve it?


Answer: The error can be ignored, your `gunicorn` package installed successfully.

The error is thrown by a bit of code that'd only work on Python 3.3 or newer,
but isn't used by older Python versions that Gunicorn supports.

See <https://github.com/benoitc/gunicorn/issues/788>:

> The error is a syntax error happening during install. It is harmless.

During installation the `setup.py` script tries to collect all files to be
installed, and compiles them to `.pyc` bytecache files. One file that is used
only on Python 3.3 or up is included in this and the compilation for that one
file fails.

The file in question adds support for the [aiohttp http client/server
package](https://pypi.python.org/pypi/aiohttp), which only works on Python 3.3
and up anyway. As such you can ignore this error entirely.

