How to position hline with "paper" coordinates?

📊 Plotly Python
1

I want to place a hline with relative coordinates to graph area, thus the “paper” coordinates. But it seems to be broken:

asdf = px.scatter([4])
asdf = asdf.add_hline(
    y=1,
    xref="paper",
    yref="paper",
    line_width=8,
    x0=0.05,
    x1=0.15
)
asdf

Is there a way how to use paper coordinates with placing lines?