def universal_set(documents, k) :
universal = OrderedSet()
universal1 = OrderedSet()
for doc in documents :
#print("doc = ", doc)
shingles, shings = k_shingles(doc, k)
universal = universal.union(shingles)
universal1 = universal1.union(shings)
universal = list(universal)
universal1 = list(universal1)
universal.sort()
universal1.sort()
universal = OrderedSet(universal)
universal1 = OrderedSet(universal1)
return universal, universal1
