While it didn’t make the cut, the Instax Square SQ1 is also worth a brief mention. Like the Mini 12, the Square SQ1 produces good-quality shots, is easy to set up and use, and features a built-in selfie mirror. The reason we didn’t include it above, however, is that it costs nearly twice as much as the Mini 12 at $159.95, though we do sometimes see it on sale for $100. That said, it might be worth a look if you prefer large 2.4 x 2.4-inch square prints and relatively true-to-life photos over vintage-looking stills. After all, the SQ1 is still cheaper than the Polaroid Flip and produces higher-quality images than the Kodak Mini Shot 3 Square Retro, which also prints similarly sized square shots.
For implementers, the locking model adds a fair amount of non-trivial internal bookkeeping. Every operation must check lock state, readers must be tracked, and the interplay between locks, cancellation, and error states creates a matrix of edge cases that must all be handled correctly.
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（三）未经许可，擅自经营按照国家规定需要由公安机关许可的行业的。
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