Simple swap smart contract in SUI

[CSzLong]

Money: 400R

Please review the code for the simple swap in SUI

Code Structure

.
├── bank
├     └── liquidity
├            ├── generate_pool
├            ├── deposit_totally
├            ├── deposit_partly
├            ├── remove_liquidity_totally
├            ├── withdraw_out
├            ├── swap_x_to_y
├            └── swap_y_to_x 
└── testcoin
       ├── cnya
       ├     └── mint_coin
       └── cnyw
             └── mint_coin

pull request: https://github.com/NonceGeek/Web3-dApp-Camp/pull/219