如何在更新期间隐藏或清除python Dash+Plotly图形

import dash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output

app = dash.Dash(__name__)

app.layout = html.Div([
    dcc.Graph(id='graph'),
    html.Button('Hide Graph', id='hide-button')
])

@app.callback(
    Output('graph', 'style'),
    [Input('hide-button', 'n_clicks')]
)
def hide_graph(n_clicks):
    if n_clicks is None:
        return {'display': 'block'}
    else:
        return {'display': 'none'}

if __name__ == '__main__':
    app.run_server(debug=True)

import dash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output

app = dash.Dash(__name__)

app.layout = html.Div([
    dcc.Graph(id='graph'),
    html.Button('Clear Graph', id='clear-button')
])

@app.callback(
    Output('graph', 'figure'),
    [Input('clear-button', 'n_clicks')]
)
def clear_graph(n_clicks):
    if n_clicks is None:
        return {'data': []}
    else:
        return {'data': []}

if __name__ == '__main__':
    app.run_server(debug=True)