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, 27 insertions, 0 deletions

diff --git a/deps/npm/node_modules/isstream/isstream.js b/deps/npm/node_modules/isstream/isstream.js
new file mode 100644
index 0000000000..a1d104a7ac
--- /dev/null
+++ b/deps/npm/node_modules/isstream/isstream.js
@@ -0,0 +1,27 @@
+var stream = require('stream')
+
+
+function isStream (obj) {
+  return obj instanceof stream.Stream
+}
+
+
+function isReadable (obj) {
+  return isStream(obj) && typeof obj._read == 'function' && typeof obj._readableState == 'object'
+}
+
+
+function isWritable (obj) {
+  return isStream(obj) && typeof obj._write == 'function' && typeof obj._writableState == 'object'
+}
+
+
+function isDuplex (obj) {
+  return isReadable(obj) && isWritable(obj)
+}
+
+
+module.exports            = isStream
+module.exports.isReadable = isReadable
+module.exports.isWritable = isWritable
+module.exports.isDuplex   = isDuplex