Backport of the concurrent.futures package to Python 2.6 and 2.7

This is a backport of the concurrent.futures standard library module to Python 2.

It does not work on Python 3 due to Python 2 syntax being used in the codebase. Python 3 users should not attempt to install it, since the package is already included in the standard library.

To conditionally require this library only on Python 2, you can do this in your setup.py:

setup(
    ...
    extras_require={
        ':python_version == "2.7"': ['futures']
    }
)

Or, using the newer syntax:

setup(
    ...
    install_requires={
        'futures; python_version == "2.7"'
    }
)