Not having anything to do with the original problem, but I'd recommend not using mips as an array and a hash. It can be very confusing for less-experienced maintainers. (Just answered an Anonymonk question with that exact issue.)

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We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.

Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.