Adding line to existing chart in dash

I wanna add a horizontal line to line chart in dash.
first i tryed as code below and it works

fig = px.line(df, y=‘Close’)


but when i wanted to use in dash, add_hline dosent work and just i can see line chart without horizontal line.

that is my function to update callback

def display_graph(pos_x):

df = drow_candle(pos_x)

fig = go.Figure()

fig.add_trace(go.Scatter(x=df.index, y=df['Close'], mode='lines'))


return fig