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Solution of ODE expressed with hyperbolic trigonometric function

With Sage 7.3, consider

t=var('t')
v=function('v')(t)
m, g, h = var('m g h')
assume(m > 0)
assume(g > 0)
assume(h > 0)
sol = desolve(m*diff(v,t) == m*g - h*v**2, v, ivar=t)
show(sol)
sol.solve(v)

The outcomes are

mlog(hv(t)ghmhv(t)+ghm)2ghm=C+t

[v(t)=ghm(e(2ghmCm+2ghmtm)+1)h(e(2ghmCm+2ghmtm)1)]

Nevermind desolve came with an implicit solution I had to further solve by hand but then solve missed that the last expression for v(t) is a mere hyperbolic tangent. How would I get the solution in its simpler form?

v(t)=gmh tanh(ghm(t+mC))

Thanks for any hint!