use isfixpoint in example

Author: hexaeder

docs/examples/init_tutorial.jl

@@ -269,6 +269,10 @@ du = ones(dim(nw_dyn))
 nw_dyn(du, uflat(u0_dyn), pflat(u0_dyn), 0.0)
 extrema(du .- zeros(dim(nw_dyn))) # very close to zero, confirming we have a steady state!
 
+# Alternatively, we can used the [`isfixpoint`](@ref) function to check if the state is a fixpoint:
+@assert isfixpoint(nw_dyn, u0_dyn)
+nothing #hide
+
 #=
 ## Simulating the Dynamic Model