Binance API- Symbols

I am using python to make a simple program that makes an order with the
create_test _order operation…
I want to make it as a function that takes three parameters of SYMBOL PAIR and amount
and makes an order like this def buy(amount: int , symbol: str, pair: str):

I keep getting invalid symbol from the way I build it .
for example I tried buying BTC with USDT or the opposite and I put in symbol parameter of the create_order symbol + quote and it keeps rejecting my pairs.
I write in capital letters too.
is there a way to request from the API in python all the allowed pairing in strings that are accepted in the create_order method?
I want to at least make another method that generates those symbols in the correct way for the SIDE_BUY operation, I try for some pairs and it works and for some it doesn’t. its really frustrating…
thanks in advance for anyone who takes the time to read and help.

You could directly use import this library GitHub - binance/binance-connector-python: a simple connector to Binance Public API ?

Or look into this script code to have an understanding how to submit a new order: binance-signature-examples/ at master · binance/binance-signature-examples · GitHub