Transforms don't execute until the consumer pulls. There's no eager evaluation, no hidden buffering. Data flows on-demand from source, through transforms, to the consumer. If you stop iterating, processing stops.
After your base implementation is complete, you MUST:
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（二）乏燃料，是指在反应堆堆芯内受过辐照并从堆芯永久卸出的核燃料。
let goal = pixel