Chain `emitter.into(target) for #3 like the other emitter methods.

Author: ryanve

src/index.js

@@ -50,12 +50,13 @@
   };
 
   /**
-   * @this {Energy|Object|Function} source emitter
-   * @param {Object|Function} target to convert into emitter
-   * @return {Object|Function} target converted into emitter
+   * @this {Object|Energy|Function} source emitter or emitter-like
+   * @param {Object|Energy|Function} target to convert into emitter
+   * @return {Object|Energy|Function} source for chaining
    */  
   emitter['into'] = function(target) {
-    return defaults(target, this);
+    defaults(target, this);
+    return this;
   };
 
   /**