Copy/Paste the following code to your GroIMP project:
//**********************************************************
/*
You will learn with this example:
– how to create a simple model of shoot growth with opposite
branching (in 3d)
– how to use elements without drawing them (module B)
*/

// architectural tree model Schoute
// I for Internode extends the turtle command F

module I(float len) extends F(len);

// B stands for a bud and is not a visible object (is not drawn)

module B(float len);

protected void init()
[
Axiom ==> B(5);
]

public void run()
[
// rotation around the up axis (RU) and around the
// head axis (RH)
B(x) ==> I(x) [ RU(30) RH(90) B(0.7*x) ]
[ RU(-30) RH(90) B(0.7*x) ];
]

//**********************************************************