module Enumerable

def cycle(n = nil)
  return to_enum(:cycle, n) unless block_given?
  n = n && Backports.coerce_to_int(n)
  if n == nil || n >= 1
    cache = []
    each do |elem|
      cache << elem
      yield elem
    end
    if n
      (n-1).times { cache.each{|e| yield e } }
    else
      loop        { cache.each{|e| yield e } }
    end unless cache.empty?
  end
  nil
end