--- /dev/null
+'use strict'
+function YError (msg) {
+ this.name = 'YError'
+ this.message = msg || 'yargs error'
+ Error.captureStackTrace(this, YError)
+}
+
+YError.prototype = Object.create(Error.prototype)
+YError.prototype.constructor = YError
+
+module.exports = YError