### 2nd-order ODE: Maxima wants sign of 1 constant before finishing

I'm trying to solve a 2nd-order nonlinear ODE using desolve(). Maxima gets partway through, but then asks for the sign of one of the integration constants. How can I tell it to assume something that doesn't exist before I call desolve()?

```
t,P,x0=var('t,P,x0')
x=function('x',t)
de=(diff(x,t,2)*x^2+P==0)
forget()
assume(P>0,x0>0)
desolve(de,x,ics=[0,x0,0],ivar=t)
```

gives the error:

```
TypeError: ECL says: Maxima asks: Is %k1 positive or negative?
```