I'm tryng to solve this ODE that was made in mathematica: htt ps://i.imgur.com/9iyAcBW.jpg

As ICS we have u(0)=0 and u'(L)=P

but in sage documentation i don't see anything to defining a point for u' different from x0 but only `ics=[x0,y(x0),y'(x0)]`

or `x0,y0,x1,y1`

how to do that? this is my code ritgh now:

```
e,a,p,L,a1,a2,r1,r2=var('e,a,p,L,a1,a2,r1,r2')
u=function('u')(x)
a1=pi()*r1**2
a2=pi()*r2**2
area(x)=a1+(a2-a1)*x/L
sol=desolve(e*diff(area,x)*diff(u,x)+e*area*diff(u,x,2)==0,u,ivar=x,ics=[0,0,diff(u,x)(L),p])
```