pattern = /\A[a-f0-9]{24}\z/
str1 = "589ab375c3c6416310171b5b"
str2 = "http://s...content-available-to-author-only...e.com/589ab375c3c6416310171b5b?review"
str3 = "589ab375c3c6416310171b5b
"
print str1.match pattern
print str2.match pattern
print str3.match pattern
cGF0dGVybiA9IC9cQVthLWYwLTldezI0fVx6LwpzdHIxID0gIjU4OWFiMzc1YzNjNjQxNjMxMDE3MWI1YiIKc3RyMiA9ICJodHRwOi8vcy4uLmNvbnRlbnQtYXZhaWxhYmxlLXRvLWF1dGhvci1vbmx5Li4uZS5jb20vNTg5YWIzNzVjM2M2NDE2MzEwMTcxYjViP3JldmlldyIKc3RyMyA9ICI1ODlhYjM3NWMzYzY0MTYzMTAxNzFiNWIKIgpwcmludCBzdHIxLm1hdGNoIHBhdHRlcm4KcHJpbnQgc3RyMi5tYXRjaCBwYXR0ZXJuCnByaW50IHN0cjMubWF0Y2ggcGF0dGVybg==