fib = lambda do |n|
    if n < 1
        return 0
    elsif n < 2 
        return 1
    else
        return fib.call(n-1) + fib.call(n-2)
    end
end

def memoize(f)
    memo = {}
    return lambda do |x|
        if memo.key?(x)
            return memo[x]
        end 
        memo[x] = f.call(x)        
        return memo[x]
    end
end

fib = memoize(fib)

10.times do |x|
    puts fib.call(x + 1)
end