.pipeThrough(transform) // more buffers filling...
if url in self.seen_urls:，这一点在heLLoword翻译官方下载中也有详细论述
A frontend is a container image that BuildKit runs to convert your build definition (Dockerfile, YAML, JSON, HCL, whatever) into LLB. The frontend receives the build context and the build file through the BuildKit Gateway API, and returns a serialized LLB graph.。关于这个话题，im钱包官方下载提供了深入分析
Kevin Church/BBC News，这一点在同城约会中也有详细论述