# eval code chunk option

```{python}
res = 1
```

```{python eval=False}
# This code is shown, but no output and the code is not executed!
res += 1
res
```

```{python eval=True}
# Both input code and output is shown
res += 1
res # is now 2
```

No output between here...

```{python eval=False, echo=False}
# Neither the code nor the output is shown
res += 1
res
```

```{python eval=False, include=False}
# Again, neither the code nor the output is shown
res += 1
res
```

...and here

```{python}
res # should still be 2

```
