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My solution is to combine the both approaches such that in the generation of the value-key. Specifically, given a key, the value-key we generate for k is translate k to a string and append is generated with these steps:

1. Create a string representation of the key.
2. Create a string of the form _XXXXXXXXXXX_XXXXXXXX, where the leftmost bunch of 11 Xs are hexadecimal digits representing the time in milliseconds and the rightmost bunch of 8 Xs are hexadecimal digits representing a random number.
3. Append the string from step 2 to the string from step 1.

Thus the generated value-key has the form <key as string>_XXXXXXXXXXX_XXXXXXXX.

Admittedly, my solution does not guarantee uniqueness, but I believe it is as close as we can get and minimizes the chance of collision.

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