#### Problem description

Please explain:
* **what** you tried to achieve,
* **how** you went about it (referring to the code sample), and
* **why** the current behaviour is a problem and what output
  you expected instead.

#### Code Sample

Create a [minimal, complete, verifiable example](https://stackoverflow.com/help/mcve).

```python
# Paste your code here.

```

#### Actual Output

#### Expected Output

#### Dependency Information

Please paste the output of `python -c "from cobra import show_versions;
show_versions()"` in the details block below.

<details>

[Paste output here.]

</details>
