diff --git a/frontend/angular-io.js b/frontend/angular-io.js
index f894bb8..f9e9b99 100644
--- a/frontend/angular-io.js
+++ b/frontend/angular-io.js
@@ -6,7 +6,7 @@
 
 
 ```
-npm install --save @angular/cli       // declarative and flexible JavaScript framework for building UI
+npm install --save @angular/cli       // install command line interface (CLI) for Angular apps
 ng serve                              // serve the app
 ng build                              // build the release
 ```
@@ -46,13 +46,15 @@ class MyModule {}
 // List of components, directives, and pipes that belong to this module.
 declarations: [MyRedComponent, MyBlueComponent, MyDatePipe] 
 
-// List of modules to import into this module. Everything from the imported modules is available to declarations of this module.
+// List of modules to import into this module. Everything from the imported modules is available 
+// to declarations of this module.
 imports: [BrowserModule, SomeOtherModule] 
 
 // List of components, directives, and pipes visible to modules that import this module.
 exports: [MyRedComponent, MyDatePipe] 
 
-// List of dependency injection providers visible both to the contents of this module and to importers of this module.
+// List of dependency injection providers visible both to the contents of this module and to 
+// importers of this module.
 providers: [MyService, { provide: ... }]  
 
 // List of components to bootstrap when this module is bootstrapped.
@@ -71,16 +73,19 @@ bootstrap: [MyAppComponent]
 // Binds attribute role to the result of expression myAriaRole.
 // <div [attr.role]="myAriaRole">  
 
-// Binds the presence of the CSS class extra-sparkle on the element to the truthiness of the expression isDelightful.
+// Binds the presence of the CSS class extra-sparkle on the element to the truthiness of the 
+// expression isDelightful.
 // <div [class.extra-sparkle]="isDelightful">  
 
 // Binds style property width to the result of expression mySize in pixels. Units are optional.
 // <div [style.width.px]="mySize"> 
 
-// Calls method readRainbow when a click event is triggered on this button element (or its children) and passes in the event object.
+// Calls method readRainbow when a click event is triggered on this button element (or its
+// children) and passes in the event object.
 // <button (click)="readRainbow($event)">  
 
-// Binds a property to an interpolated string, for example, "Hello Seabiscuit". Equivalent to: <div [title]="'Hello ' + ponyName">
+// Binds a property to an interpolated string, for example, "Hello Seabiscuit". 
+// Equivalent to: <div [title]="'Hello ' + ponyName">
 // <div title="Hello {{ponyName}}">  
 
 // Binds text content to an interpolated string, for example, "Hello Seabiscuit".
@@ -89,21 +94,25 @@ bootstrap: [MyAppComponent]
 // Sets up two-way data binding. Equivalent to: <my-cmp [title]="name" (titleChange)="name=$event">
 // <my-cmp [(title)]="name"> 
 
-// Creates a local variable movieplayer that provides access to the video element instance in data-binding and event-binding expressions in the current template.
+// Creates a local variable movieplayer that provides access to the video element instance in 
+// data-binding and event-binding expressions in the current template.
 // <video #movieplayer ...>
 // <button (click)="movieplayer.play()">
 // </video>  
 
-// The * symbol turns the current element into an embedded template. Equivalent to: <ng-template [myUnless]="myExpression"><p>...</p></ng-template>
+// The * symbol turns the current element into an embedded template. 
+// Equivalent to: <ng-template [myUnless]="myExpression"><p>...</p></ng-template>
 // <p *myUnless="myExpression">...</p> 
 
 // Transforms the current value of expression cardNumber via the pipe called myCardNumberFormatter.
 // <p>Card No.: {{cardNumber | myCardNumberFormatter}}</p> 
 
-// The safe navigation operator (?) means that the employer field is optional and if undefined, the rest of the expression should be ignored.
+// The safe navigation operator (?) means that the employer field is optional and if undefined, 
+// the rest of the expression should be ignored.
 // <p>Employer: {{employer?.companyName}}</p>  
 
-// An SVG snippet template needs an svg: prefix on its root element to disambiguate the SVG element from an HTML component.
+// An SVG snippet template needs an svg: prefix on its root element to disambiguate the SVG 
+// element from an HTML component.
 // <svg:rect x="0" y="0" width="100" height="100"/>  
 
 // An <svg> root element is detected as an SVG element automatically, without the prefix.
@@ -123,20 +132,24 @@ import { CommonModule } from '@angular/common';
 // Removes or recreates a portion of the DOM tree based on the showSection expression.
 // <section *ngIf="showSection"> 
 
-// Turns the li element and its contents into a template, and uses that to instantiate a view for each item in list.
+// Turns the li element and its contents into a template, and uses that to instantiate a view for
+// each item in list.
 // <li *ngFor="let item of list">  
 
-// Conditionally swaps the contents of the div by selecting one of the embedded templates based on the current value of conditionExpression.
+// Conditionally swaps the contents of the div by selecting one of the embedded templates based on 
+// the current value of conditionExpression.
 // <div [ngSwitch]="conditionExpression">
 // <ng-template [ngSwitchCase]="case1Exp">...</ng-template>
 // <ng-template ngSwitchCase="case2LiteralString">...</ng-template>
 // <ng-template ngSwitchDefault>...</ng-template>
 // </div>  
 
-// Binds the presence of CSS classes on the element to the truthiness of the associated map values. The right-hand expression should return {class-name: true/false} map.
+// Binds the presence of CSS classes on the element to the truthiness of the associated map 
+// values. The right-hand expression should return {class-name: true/false} map.
 // <div [ngClass]="{'active': isActive, 'disabled': isDisabled}">  
 
-// Allows you to assign styles to an HTML element using CSS. You can use CSS directly, as in the first example, or you can call a method from the component.
+// Allows you to assign styles to an HTML element using CSS. You can use CSS directly, as in the
+// first example, or you can call a method from the component.
 // <div [ngStyle]="{'property': 'value'}">
 // <div [ngStyle]="dynamicStyles()"> 
 
@@ -172,7 +185,8 @@ class MyDirective() {}
 @Pipe({...})
 class MyPipe() {} 
 
-// Declares that a class has dependencies that should be injected into the constructor when the dependency injector is creating an instance of this class.
+// Declares that a class has dependencies that should be injected into the constructor when the 
+// dependency injector is creating an instance of this class.
 @Injectable()
 class MyService() {}  
 
@@ -184,7 +198,8 @@ class MyService() {}
 
 @Directive({ property1: value1, ... })
 
-// Specifies a CSS selector that identifies this directive within a template. Supported selectors include element, [attribute], .class, and :not().
+// Specifies a CSS selector that identifies this directive within a template. Supported selectors
+// include element, [attribute], .class, and :not().
 selector: '.cool-button:not(a)' 
 
 // Does not support parent-child relationship selectors.
@@ -223,28 +238,36 @@ styleUrls: ['my-component.css']
 
 import { Input, ... } from '@angular/core';
 
-// Declares an input property that you can update via property binding (example: <my-cmp [myProperty]="someExpression">).
+// Declares an input property that you can update via property binding 
+// (example: <my-cmp [myProperty]="someExpression">).
 @Input() myProperty;  
 
-// Declares an output property that fires events that you can subscribe to with an event binding (example: <my-cmp (myEvent)="doSomething()">).
+// Declares an output property that fires events that you can subscribe to with an event binding 
+// (example: <my-cmp (myEvent)="doSomething()">).
 @Output() myEvent = new EventEmitter(); 
 
-// Binds a host element property (here, the CSS class valid) to a directive/component property (isValid).
+// Binds a host element property (here, the CSS class valid) to a directive/component property 
+// (isValid).
 @HostBinding('class.valid') isValid;  
 
-// Subscribes to a host element event (click) with a directive/component method (onClick), optionally passing an argument ($event).
+// Subscribes to a host element event (click) with a directive/component method (onClick), 
+// optionally passing an argument ($event).
 @HostListener('click', ['$event']) onClick(e) {...} 
 
-// Binds the first result of the component content query (myPredicate) to a property (myChildComponent) of the class.
+// Binds the first result of the component content query (myPredicate) to a property 
+// (myChildComponent) of the class.
 @ContentChild(myPredicate) myChildComponent;  
 
-// Binds the results of the component content query (myPredicate) to a property (myChildComponents) of the class.
+// Binds the results of the component content query (myPredicate) to a property 
+// (myChildComponents) of the class.
 @ContentChildren(myPredicate) myChildComponents;  
 
-// Binds the first result of the component view query (myPredicate) to a property (myChildComponent) of the class. Not available for directives.
+// Binds the first result of the component view query (myPredicate) to a property 
+// (myChildComponent) of the class. Not available for directives.
 @ViewChild(myPredicate) myChildComponent; 
 
-// Binds the results of the component view query (myPredicate) to a property (myChildComponents) of the class. Not available for directives.
+// Binds the results of the component view query (myPredicate) to a property (myChildComponents)
+// of the class. Not available for directives.
 @ViewChildren(myPredicate) myChildComponents; 
 
 
@@ -254,7 +277,8 @@ import { Input, ... } from '@angular/core';
 
 // (implemented as class methods)
 
-// Called before any other lifecycle hook. Use it to inject dependencies, but avoid any serious work here.
+// Called before any other lifecycle hook. Use it to inject dependencies, but avoid any serious 
+// work here.
 constructor(myService: MyService, ...) { ... }  
 
 // Called after every change to input properties and before processing content or child views.
@@ -263,7 +287,8 @@ ngOnChanges(changeRecord) { ... }
 // Called after the constructor, initializing input properties, and the first call to ngOnChanges.
 ngOnInit() { ... }  
 
-// Called every time that the input properties of a component or a directive are checked. Use it to extend change detection by performing a custom check.
+// Called every time that the input properties of a component or a directive are checked. Use it
+// to extend change detection by performing a custom check.
 ngDoCheck() { ... } 
 
 // Called after ngOnInit when the component's or directive's content has been initialized.
@@ -272,10 +297,12 @@ ngAfterContentInit() { ... }
 // Called after every check of the component's or directive's content.
 ngAfterContentChecked() { ... } 
 
-// Called after ngAfterContentInit when the component's views and child views / the view that a directive is in has been initialized.
+// Called after ngAfterContentInit when the component's views and child views / the view that a 
+// directive is in has been initialized.
 ngAfterViewInit() { ... } 
 
-// Called after every check of the component's views and child views / the view that a directive is in.
+// Called after every check of the component's views and child views / the view that a directive 
+// is in.
 ngAfterViewChecked() { ... }  
 
 // Called once, before the instance is destroyed.
@@ -315,21 +342,26 @@ const routes: Routes = [
   { path: ..., component: ..., data: { message: 'Custom' } }
 ]);
 
-// Configures routes for the application. Supports static, parameterized, redirect, and wildcard routes. Also supports custom route data and resolve.
+// Configures routes for the application. Supports static, parameterized, redirect, and wildcard 
+// routes. Also supports custom route data and resolve.
 const routing = RouterModule.forRoot(routes); 
 
 // Marks the location to load the component of the active route.
 // <router-outlet></router-outlet>
 // <router-outlet name="aux"></router-outlet>
 
-// Creates a link to a different view based on a route instruction consisting of a route path, required and optional parameters, query parameters, and a fragment. To navigate to a root route, use the / prefix; for a child route, use the ./prefix; for a sibling or parent, use the ../ prefix.
+// Creates a link to a different view based on a route instruction consisting of a route path, 
+// required and optional parameters, query parameters, and a fragment. To navigate to a root 
+// route, use the / prefix; for a child route, use the ./prefix; for a sibling or parent, use the 
+// ../ prefix.
 // <a routerLink="/path">
 // <a [routerLink]="[ '/path', routeParam ]">
 // <a [routerLink]="[ '/path', { matrixParam: 'value' } ]">
 // <a [routerLink]="[ '/path' ]" [queryParams]="{ page: 1 }">
 // <a [routerLink]="[ '/path' ]" fragment="anchor">
 
-// The provided classes are added to the element when the routerLink becomes the current active route.
+// The provided classes are added to the element when the routerLink becomes the current active
+// route.
 // <a [routerLink]="[ '/path' ]" routerLinkActive="active">  
 
 class CanActivateGuard implements CanActivate {
@@ -339,7 +371,9 @@ class CanActivateGuard implements CanActivate {
   ): Observable<boolean>|Promise<boolean>|boolean { ... }
 }
 
-// An interface for defining a class that the router should call first to determine if it should activate this component. Should return a boolean or an Observable/Promise that resolves to a boolean.
+// An interface for defining a class that the router should call first to determine if it should 
+// activate this component. Should return a boolean or an Observable/Promise that resolves to a 
+// boolean.
 {
   path: ...,
   canActivate: [CanActivateGuard]
@@ -353,7 +387,9 @@ class CanDeactivateGuard implements CanDeactivate<T> {
   ): Observable<boolean>|Promise<boolean>|boolean { ... }
 }
 
-// An interface for defining a class that the router should call first to determine if it should deactivate this component after a navigation. Should return a boolean or an Observable/Promise that resolves to a boolean.
+// An interface for defining a class that the router should call first to determine if it should 
+// deactivate this component after a navigation. Should return a boolean or an Observable/Promise 
+// that resolves to a boolean.
 {
   path: ...,
   canDeactivate: [CanDeactivateGuard]
@@ -366,7 +402,9 @@ class CanActivateChildGuard implements CanActivateChild {
   ): Observable<boolean>|Promise<boolean>|boolean { ... }
 }
 
-// An interface for defining a class that the router should call first to determine if it should activate the child route. Should return a boolean or an Observable/Promise that resolves to a boolean.
+// An interface for defining a class that the router should call first to determine if it should 
+// activate the child route. Should return a boolean or an Observable/Promise that resolves to a 
+// boolean.
 {
   path: ...,
   canActivateChild: [CanActivateGuard],
@@ -380,7 +418,9 @@ class ResolveGuard implements Resolve<T> {
   ): Observable<any>|Promise<any>|any { ... }
 }
 
-// An interface for defining a class that the router should call first to resolve route data before rendering the route. Should return a value or an Observable/Promise that resolves to a value.
+// An interface for defining a class that the router should call first to resolve route data 
+// before rendering the route. Should return a value or an Observable/Promise that resolves to a 
+// value.
 {
   path: ...,
   resolve: [ResolveGuard]
@@ -392,7 +432,9 @@ class CanLoadGuard implements CanLoad {
   ): Observable<boolean>|Promise<boolean>|boolean { ... }
 }
 
-// An interface for defining a class that the router should call first to check if the lazy loaded module should be loaded. Should return a boolean or an Observable/Promise that resolves to a boolean.
+// An interface for defining a class that the router should call first to check if the lazy loaded 
+// module should be loaded. Should return a boolean or an Observable/Promise that resolves to a 
+// boolean.
 {
   path: ...,
   canLoad: [CanLoadGuard],