text: from dash.dependencies import Input, Output
  import dash_html_components as html
  import dash_core_components as dcc
  
  from app import app
  
  layout = html.Div([
      html.H3('App 1'),
      dcc.Dropdown(
          id='app-1-dropdown',
          options=[
              {'label': 'App 1 - {}'.format(i), 'value': i} for i in [
                  'NYC', 'MTL', 'LA'
              ]
          ]
      ),
      html.Div(id='app-1-display-value'),
      dcc.Link('Go to App 2', href='/apps/app2')
  ])
  
  
  @app.callback(
      Output('app-1-display-value', 'children'),
      [Input('app-1-dropdown', 'value')])
  def display_value(value):
      return 'You have selected "{}"'.format(value)
  