# Create a class call "mom" and 
# add a member function call "greet"
Class mom
mom instproc greet {} {
    $self instvar age_
    puts "$age_ years old mom say:
    How are you doing?"
}

# Create a child class of "mom" called "kid" 
# and overide the member function "greet"
Class kid -superclass mom
kid instproc greet {} {
    $self instvar age_
    puts "$age_ years old kid say:
    What's up, dude?"
}

# Create a mom and a kid object set each age
set a [new mom]
$a set age_ 45
set b [new kid]
$b set age_ 15

# Calling member function "greet" of each object
$a greet
$b greet