Batch swaps are a single function call to Balancer's Vault, which then updates the balance of the Pools.
The Vault accounts for token balances, while the Swaps contract implements the logic behind swaps, joins, and exits.
批量交换是对 Balancer Vault 的单个函数调用，然后会更新池的余额。
Vault 负责代币余额，而 Swaps 合约实现了交换、加入和退出背后的逻辑。