How use Systems.henonheiles from InteractiveDynamics

I’m trying to duplicate the first example of trajectory evolution in the docs for the InteractiveDynamcis package (Trajectory Evolution · InteractiveDynamics).

I’ve already created an environment into which I’ve added InteractiveDynamics, DynamicalSystems, GLMakie, OrdinaryDiffEq,

In that environment, I executed:

using InteractiveDynamics
using DynamicalSystems, GLMakie
using OrdinaryDiffEq

But when I try to execute next…

ds = Systems.henonheiles()

… I get error:

ERROR: UndefVarError: Systems not defined
Stacktrace:
 [1] top-level scope

What is Systems?

I tried to add a package named Systems but no such package was found.