### Maxima wants to know whether %k1 is positve or negative

Trying to solve a differential equation in Sage:

```
sage: de = -diff(y, x, 2) - G*M/y^2
sage: desolve(de, y, ics=[0, 1000])
```

I get a type error and a question:

```
TypeError: Computation failed since Maxima requested additional constraints; using the 'assume' command before evaluation *may* help (example of legal syntax is 'assume(%k1>0)', see `assume?` for more details)
Is %k1 positive or negative?
```

But when I use `assume(%k1>0)`

I get a syntax error,
saying that there's something wrong with the percent sign.