gistfile1.txt

>>> python2 -m timeit -s 'r = {1, 2, 3}; s = {4, 5, 6}; t = {7, 8, 9}' '3 in reduce(lambda x,y :x.union(y),[r,s,t])'
1000000 loops, best of 3: 1.01 usec per loop

>>> python2 -m timeit -s 'r = {1, 2, 3}; s = {4, 5, 6}; t = {7, 8, 9}' '3 in r|s|t'
1000000 loops, best of 3: 0.399 usec per loop

>>> python2 -m timeit -s 'r = {1, 2, 3}; s = {4, 5, 6}; t = {7, 8, 9}' '3 in set().union(r, s, t)'
1000000 loops, best of 3: 0.407 usec per loop

>>> python2 -m timeit -s 'r = {1, 2, 3}; s = {4, 5, 6}; t = {7, 8, 9}' 'any(3 in item for item in [r,s,t])'
1000000 loops, best of 3: 0.621 usec per loop

>>> python2 -m timeit -s 'r = {1, 2, 3}; s = {4, 5, 6}; t = {7, 8, 9}' '3 in r.union(s).union(t)'
1000000 loops, best of 3: 0.528 usec per loop