Test your muppets with the following code:

| frogMuppet grouchMuppet |
frogMuppet := FrogMuppet new initialize.
grouchMuppet := GrouchMuppet new initialize.
frogMuppet name: 'Kermit the Frog'.
grouchMuppet name: 'Oscar the Grouch'.
frogMuppet greet.
grouchMuppet greet.