new_contents: from .footer import footer
  from .navbar import navbar
  import dash_html_components as html
  import dash_core_components as dcc
  import dash_bootstrap_components as dbc
  
  
  layout = html.Div([
      dcc.Location(id='url', refresh=False),
      navbar,
      dbc.Container(id='page-content', className='mt-4'),
      html.Hr(),
      footer
  ])
subject: Add component.layout