zerop(0) is
  true
end
zerop(_) is
  false
end

fib(0) is
  1
end
fib(1) is
  1
end
fib(x) is
  fib(x-1) + fib(x-2)
end

add(x, y) is
  x + y
end

puts add(1, 2)
puts fib(5)

putser(string) is
  puts string
end
putser("foo")

varity(_) is
  puts "one thing"
end
varity(_, _) is
  puts "two things"
end
varity(1)
varity(1,2)