class Quad
end

class Rect < Quad
end

class Square < Rect
end

class Trap < Quad
end

class Rhomb < Trap
end

def test
    squa = Square.new
    rhomb = Rhomb.new
    puts squa.is_a?(Rect) == true
    puts squa.is_a?(Quad) == true
    puts rhomb.is_a?(Trap) == true
    puts rhomb.is_a?(Quad) == true
end

test