IsTimedependent(::Type{<:Any}) = Val(false)
IsTimedependent(f) = IsTimedependent(typeof(f))

## If IsTimedependent is true the type should support the function `wrapped_value`

struct Timedependent{T}
    a::T
end

wrapped_value(a::Timedependent) = a.a
IsTimedependent(::Type{<:Timedependent}) = Val(true)

(tf::Timedependent)(x...) = tf.f(x...)


eval_on(g, f) = eval_on(g, f, IsTimedependent(f))

function eval_on(g,f,::Val{false})
    ## Same as current
end

function eval_on(g,f,::Val{true})
    return t->eval_on(g, x̄->wrapped_value(f)(t,x̄))
end