title: discord.py get a server prefix from .json file
body: <p>I just got into coding discord bots using discord.py (Python 3.8; discord.py 1.5.1) and I ran into a problem. I want to give the user the server prefix when he/she uses my custom help command (which just returns a string with all commands and the prefix). I have stored the prefixes of servers in a .json file, but how can I return the server prefix from that file?</p>
  <p>Tell me if you need some parts of my code to be able to find a solution.</p>