title: ngrx ofType, @ngrx/effects
body: <p>i try to understand how typeof effects work under the hood in ngrx,
  if i declare in my app module: </p>
  
  <pre><code>....
  
  @NgModule({
      imports: [
          EffectsModule.forRoot([TodosEffectsService])
  ],
  
  ....
  </code></pre>
  
  <p>and i write effect file sure:</p>
  
  <pre><code>@Effect() createTodos$ = this.actions$
  .ofType(CREATE_TASK)
      .map(() =&gt; {
          console.log('called');
              return { type: 'OTHER'};
  });
  
  @Effect() addTodos$ = this.actions$
  .ofType(CREATE_TASK)
      .map(() =&gt; {
          console.log('called');
              return { type: 'OTHER'};
  });
  </code></pre>
  
  <p>i try to understand, now in run time i dispatch a action
  this.action$ is subscribed and every time execute ofType to match the type?
  or ofType once execute!?</p>
  
  <p>if it called once, when i dispatch action how effects know every time witch effect to subscribe/execute?</p>
  
  <p>thank all!</p>