Upload component dash example is not working

Hi All,

I am using below example to upload the file and generate table

https://github.com/plotly/dash-core-components/pull/73
uploading component is working fine but it is not generating the table.

layout_page_5 = html.Div([
        html.Div(id='waitfor'),
        dcc.Upload(
                id='upload',
                children=html.Div([
                        'Drag and Drop or ',
                        html.A('Select a File')
                        ]),
            style={
                    'width': '100%',
                    'height': '60px',
                    'lineHeight': '60px',
                    'borderWidth': '1px',
                    'borderStyle': 'dashed',
                    'borderRadius': '5px',
                    'textAlign': 'center',
                    'margin': '10px'
                    }
            ),
        html.Div(id='output'),
        html.Div(dt.DataTable(rows=[{}]), style={'display': 'none'}),
        html.Br(),
        dcc.Link('Navigate to "/"', href='/'),
        html.Br(),
        dcc.Link('Navigate to Bar-charts for Categorical Variable', href='/Bar-charts'),
        html.Br(),
        dcc.Link('Navigate to Histogram-charts for Continuous Variable', href='/Histogram-charts'),
        html.Br(),
        dcc.Link('Navigate to Scatter-plots b/w Target Variable & Continuous Variables', href='/Scatter-charts'),            
        html.Br(),
        dcc.Link('Navigate to Histogram-charts for Target Variable & Categorical Variables', href='/Histocat-charts'),                
        ])

@app.callback(Output('output', 'children'),
              [Input('upload', 'contents')])
def update_output(contents):
    if contents is not None:
        content_type, content_string = contents.split(',')
        if 'csv' in content_type:
            df = pd.read_csv(io.StringIO(base64.b64decode(content_string).decode('utf-8')))
            return html.Div([
                dt.DataTable(rows=df.to_dict('records'))
            ])

Please help