Why does stamen terrain return an error in my web app code?

code:

import foliummap = folium.Map(location=[38.58, -99.09],zoom_start=6, tiles="Stamen Terrain")map.save("Map1.html")

error:

File "C:\Users\Koku Lwanga\PycharmProjects\webmap\map1.py", line 2, in <module>    map = folium.Map(location=[38.58, -99.09],zoom_start=6, tiles="Stamen Terrain")          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  File "C:\Users\Koku Lwanga\PycharmProjects\webmap\venv\Lib\site-packages\folium\folium.py", line 303, in __init__    tile_layer = TileLayer(                 ^^^^^^^^^^  File "C:\Users\Koku Lwanga\PycharmProjects\webmap\venv\Lib\site-packages\folium\raster_layers.py", line 145, in __init__    raise ValueError("Custom tiles must have an attribution.")ValueError: Custom tiles must have an attribution.

I tried to add points to the map using tiles but it did not work