### Assumption that n is positive integer

I wrote

```
assume(n, 'integer')
assume(n>0)
assumptions()
```

Sage gave back

```
[n is integer, n > 0]
```

Yet the command

```
n.is_integer()
```

returned false. Also, the assumptions were not used in later computations. For example

```
gamma(-n)
```

did not return infinity.