Hello Pumas team; I guess I have a problem with the simulation. Most of the code is taken from the tutorial part, some additional parameters added.

I have the issue as: MethodError: objects of type NamedTuple{(:Ka, :K2, :CL, :Vd),NTuple{4,Float64}} are not callable

Any suggestions?

```
using Pumas, Plots, DifferentialEquations
using StochasticDiffEq
p = ParamSet((θ = VectorDomain(4, lower = zeros(4)),
Ω = PSDDomain(2)))
function randomfx(p)
ParamSet((η=MvNormal(p.Ω),))
end
function pre_f(params, randoms, subj)
θ = params.θ
η = randoms.η
(
Ka = θ[1],
K2 = θ[2],
CL = θ[3]*exp(η[1]),
Vd = θ[4]*exp(η[2])
)
end
# define the stochastic equations here
function f(du, u, p, t)
depot1, depot2, central = u
du[1] = p.Ka * depot1
du[2] = p.K2 * depot2
du[3] = (p.Ka*depot1 + p.K2*depot2) - (p.CL/p.Vd)*central
end
function g(du, u, p, t)
du[1] = 0.4*u[1]
du[2] = 0.0
du[3] = 0.5*u[3]
end
prob = SDEProblem(f, g, nothing, nothing)
init_f = (t, c) -> [0.0, 0.0]
function derived_f(c, sol, obstimes, subj)
central = sol(obstimes; idxs=5)
conc = @. central/c.V
(conc=conc, )
end
stoch_model = Pumas.PumasModel(p, randomfx, pre_f, init_f, prob, derived_f)
pop = Population([Subject(evs= DosageRegimen(10, time = 0)) for i in 1:5])
param = (θ = [
0.3,
0.2,
1.3,
64.7
],
Ω = [1.0 0.0; 0.0 1.0])
###
obs = simobs(stoch_model, pop, param, alg=SOSRI())
```