Bump to v4.0.0.

internal/stackDelete.js

@@ -0,0 +1,19 @@
+import assocDelete from './assocDelete';
+
+/**
+ * Removes `key` and its value from the stack.
+ *
+ * @private
+ * @name delete
+ * @memberOf Stack
+ * @param {string} key The key of the value to remove.
+ * @returns {boolean} Returns `true` if the entry was removed, else `false`.
+ */
+function stackDelete(key) {
+  var data = this.__data__,
+      array = data.array;
+
+  return array ? assocDelete(array, key) : data.map['delete'](key);
+}
+
+export default stackDelete;