to bottle :i
    if :i = 0 [output [No more bottles of beer]]
    if :i = 1 [output [One bottle of beer]]
    output se :i [bottles of beer]
end

to verse :i
    pr (se bottle :i [ on the wall,] bottle :i)
    pr [Take one down, pass it around]
    pr se bottle :i - 1 [ on the wall]
end

to sing :i
    if :i = 0 [stop]
    verse :i
    sing :i - 1
end

#Using it:
sing 99