Documented generators and fixed some bugs

src/classes/MidiEvent.ts

@@ -66,8 +66,7 @@ export class MidiEvent extends AudibleEvent {
       return funcResult;
     } else {
       func(this.values);
-      this.update();
-      return this;
+      return this.update();
     }
   };
 
@@ -83,7 +82,7 @@ export class MidiEvent extends AudibleEvent {
     return this;
   };
 
-  update = (): void => {
+  update = (): this => {
     const filteredValues = filterObject(this.values, [
       "key",
       "pitch",
@@ -112,6 +111,7 @@ export class MidiEvent extends AudibleEvent {
     
     this.values.note = newArrays.note;
     if (newArrays.bend) this.values.bend = newArrays.bend;
+    return this;
   };
 
   out = (): void => {