text: #https://dash.plotly.com/performance
  import datetime
  import os
  
  import dash
  import dash_core_components as dcc
  import dash_html_components as html
  from dash.dependencies import Input, Output
  from flask_caching import Cache
  
  external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']
  
  app = dash.Dash(__name__, external_stylesheets=external_stylesheets)
  cache = Cache(app.server, config={
      # try 'filesystem' if you don't want to setup redis
      'CACHE_TYPE': 'redis',
      'CACHE_REDIS_URL': os.environ.get('REDIS_URL', '')
  })
  app.config.suppress_callback_exceptions = True
  
  timeout = 20
  app.layout = html.Div([
      html.Div(id='flask-cache-memoized-children'),
      dcc.RadioItems(
          id='flask-cache-memoized-dropdown',
          options=[
              {'label': 'Option {}'.format(i), 'value': 'Option {}'.format(i)}
              for i in range(1, 4)
          ],
          value='Option 1'
      ),
      html.Div('Results are cached for {} seconds'.format(timeout))
  ])
  