可读流
Readable streams are an abstraction for a source from which data is consumed.
Examples of Readable streams include:
- HTTP responses, on the client
 - HTTP requests, on the server
 - fs read streams
 - zlib streams
 - crypto streams
 - TCP sockets
 - child process stdout and stderr
 process.stdin
All Readable streams implement the interface defined by the
stream.Readable class.