Correct name of classIsDirectlyExtended method [fix]

lib/isDirectlyExtended.js

@@ -17,7 +17,7 @@ const {validateClass, validateInstance} = require('./shared.js'),
 module.exports = {
 	isDirectlyExtended,
 	isDirectlyExtendedProto,
-	classisDirectlyExtended,
+	classIsDirectlyExtended,
 	instanceisDirectlyExtended
 };
 
@@ -28,7 +28,7 @@ module.exports = {
  */
 function isDirectlyExtended() {
 	// eslint-disable-next-line no-invalid-this
-	return classisDirectlyExtended(this);
+	return classIsDirectlyExtended(this);
 }
 
 /**
@@ -48,15 +48,15 @@ function isDirectlyExtendedProto() {
  */
 function instanceisDirectlyExtended(instance) {
 	validateInstance(instance);
-	return classisDirectlyExtended(instance.constructor);
+	return classIsDirectlyExtended(instance.constructor);
 }
 
 /**
  * Check if a class has been extended directly (with any extension).
  * @param {function} Class - Class
  * @returns {boolean} - `true` if extension directly
  */
-function classisDirectlyExtended(Class) {
+function classIsDirectlyExtended(Class) {
 	validateClass(Class);
 	return hasOwnProperty(Class, EXTENSIONS);
 }