500 Internal Server Error

Hey, this is my first time using FastAPI. I’ve started with the docs but I am not able to execute the first code snippet. The applications starts but when I go to my browser it shows me Internal Server Error.

INFO:     Started server process [18501]
INFO:     Waiting for application startup.
INFO:     ASGI 'lifespan' protocol appears unsupported.
INFO:     Application startup complete.
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
ERROR:    Exception in ASGI application
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/uvicorn/protocols/http/httptools_impl.py", line 385, in run_asgi
    result = await app(self.scope, self.receive, self.send)
  File "/usr/lib/python3/dist-packages/uvicorn/middleware/proxy_headers.py", line 45, in __call__
    return await self.app(scope, receive, send)
TypeError: root() takes 0 positional arguments but 3 were given
INFO:     127.0.0.1:34956 - "GET / HTTP/1.1" 500 Internal Server Error

FastAPI version : 0.63.0 Python version : 3.8.6