deps: upgrade npm to 6.1.0

PR-URL: https://github.com/nodejs/node/pull/20190
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/deps/npm/node_modules/is-stream/index.js b/deps/npm/node_modules/is-stream/index.js
new file mode 100644
index 0000000000..6f7ec91a40
--- /dev/null
+++ b/deps/npm/node_modules/is-stream/index.js
@@ -0,0 +1,21 @@
+'use strict';
+
+var isStream = module.exports = function (stream) {
+	return stream !== null && typeof stream === 'object' && typeof stream.pipe === 'function';
+};
+
+isStream.writable = function (stream) {
+	return isStream(stream) && stream.writable !== false && typeof stream._write === 'function' && typeof stream._writableState === 'object';
+};
+
+isStream.readable = function (stream) {
+	return isStream(stream) && stream.readable !== false && typeof stream._read === 'function' && typeof stream._readableState === 'object';
+};
+
+isStream.duplex = function (stream) {
+	return isStream.writable(stream) && isStream.readable(stream);
+};
+
+isStream.transform = function (stream) {
+	return isStream.duplex(stream) && typeof stream._transform === 'function' && typeof stream._transformState === 'object';
+};