“Conceptually, a stream is a (potentially never-ending) flow of data records, and a transformation is an operation that takes one or more streams as input, and produces one or more output streams as a result.”
“从概念上讲，流是一种（可能永无止境的）数据流记录，转换是一种将一个或多个流作为输入并因此产生一个或多个输出流的操作”。