How to solve an ODE giving ics as y'(x1) and not y'(x0) ?

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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 e a(L) 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,e*area(L)*diff(u,x)(L),p])