To use steamleaderboards as a library, first install it via PyPI:

$ # If you're using pip in a venv on 
$ .venv/bin/pip install steamleaderboards --upgrade

$ # If you're using poetry 
$ poetry add steamleaderboards

Then, create a LeaderboardGroup for the desired game.

import steamleaderboards as sl
lbgroup = sl.LeaderboardGroup(STEAM_APP_ID)

Once you have created the LeaderboardGroup, you can retrieve the desired leaderboards by using the LeaderboardGroup.get method.
You can specify the name, the display name or the id of the leaderboard to retrieve.

leaderboard_a = lbgroup.get(name=LEADERBOARD_NAME)
leaderboard_b = lbgroup.get(lbid=LEADERBOARD_ID)
leaderboard_c = lbgroup.get(display_name=LEADERBOARD_DISPLAY_NAME)

When you have the Leaderboard object, you can find all the entries in the Leaderboard.entries field, or you can search for a specific one through the Leaderboard.find_entry method.

all_scores = leaderboard_a.entries
my_score = leaderboard_a.find_entry(MY_STEAMID_1)
first_place_score = leaderboard_a.find_entry(rank=1)
last_place_score = leaderboard_a.find_entry(rank=-1)