### Details for the issue

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### Useful extra information

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#### I'm opening this issue because:

- [ ] PuLP has a bug
- [ ] PuLP needs a feature
- [ ] PuLP has another problem

#### I'm using PuLP on:

- [ ] Windows: ( _version:_ ___ )
- [ ] Linux: ( _distro:_ ___ )
- [ ] Mac OS: ( _version:_ ___ )
- [ ] Other: ___

#### I'm using python version:

- [ ] 2.7
- [ ] 3.4
- [ ] 3.5
- [ ] 3.6
- [ ] Other: ___

#### I installed PuLP via:

- [ ] pypi (pip install pulp)
- [ ] github (pip install -U git+https://github.com/coin-or/pulp)
- [ ] Other: ___

#### I have also:

- [ ] Tried out the latest github version: https://github.com/coin-or/pulp
- [ ] Searched for an existing similar issue: https://github.com/coin-or/pulp/issues?utf8=%E2%9C%93&q=is%3Aissue%20
