Node.js stdio uses ReadStream and WriteStream types, but stdio isn't always a tty.ReadStream

[davidmurdoch]

DefinitelyTyped/types/node/process.d.ts

Lines 10 to 11 in e90827e

	interface ReadStream extends tty.ReadStream {}
	interface WriteStream extends tty.WriteStream {}

tty.ReadStream type defines isTTY as "a boolean that is always true"... but sometimes it not defined at all, as stderr and stdout are not always a TTY; sometimes they are just a Socket.