[("MLGuy42", "andrew@gmail.com", "123-4567"),
("CS229DungeonMaster", "123-4567", "ml@stanford.edu"),
("Doomguy", "john@oculus.com", "carmack@gmail.com"),
("andrew26", "andrew@gmail.com", "mlguy@gmail.com")]

[[0, 1, 3], [2]]

def find_duplicates(user_info):
    results = list()
    seen = dict()
    for i, user in enumerate(user_info):
        first_seen = True
        key_info = None
        for info in user:
            if info in seen:
                first_seen = False
                key_info = info
                break
        if first_seen:
            results.append([i])
            pos = len(results) - 1
        else:
            index = seen[key_info]
            results[index].append(i)
            pos = index
        for info in user:
            seen[info] = pos
    return results

def find_duplicates(user_info):
    results = list()
    seen = dict()
    for i, user in enumerate(user_info):
        for info in user:
            if info in seen:
                index = seen[info]
                results[index].append(i)
                pos = index
                break
        else:
            results.append([i])
            pos = len(results) - 1
        for info in user:
            seen[info] = pos
    return results

from random import randrange
from timeit import timeit
MAXVALUE = 1000

for a in range(5): #I wanted to make sure I checked 5 to make sure I don't get a outlier data set that effects my ability to use timeit reasonably.
    user_info = [[randrange(MAXVALUE) for i in range(3)] for _ in range(1000)]
    print(timeit(lambda: find_duplicates(user_info), number=10000))

import unittest
#import or paste your function here

a = ('a', 'a@a', '1')
b = ('b', 'b@b', '2')
c = ('c', 'c@c', '3')
ab = ('a', 'b@b', '12')

tests = [
    ([a, b], [[0], [1]]),
    ([a, b, c], [[0], [1], [2]]),
    ([a, b], [[0], [1]]),
    ([a, ab, b], [[0, 1, 2]]),
    ([a, ab, b, c], [[0, 1, 2],[3]]),
    ([a, ab, c, b], [[0, 1, 3],[2]]),
    ([c, a, ab, b], [[0],[1, 2, 3]]),
    ([a, b, ab], [[0, 1, 2]]),
    ]

class Test(unittest.TestCase):

    def test_some(self):
        for n, t in enumerate(tests):
            ud = t[0]
            ref = t[1]
            res = find_duplicates(ud)
            assert ref==res, "n:{}, ud:{}, ref:{}, res:{}".format(n, ud, ref, res)

if __name__ == "__main__":
    unittest.main()

======================================================================
FAIL: test_some (user_info.Test)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:UsersVerenaworkspaceuser_infosrcuser_info.py", line xx, in test_some
    assert ref==res, "n:{}, ud:{}, ref:{}, res:{}".format(n, ud, ref, res)
AssertionError: n:7, ud:[('a', 'a@a', '1'), ('b', 'b@b', '2'), ('a', 'b@b', '12')], ref:[[0, 1, 2]], res:[[0, 2], [1]]

----------------------------------------------------------------------
Ran 1 test in 0.001s