slate 是被管理“交易”的封装，下面几个方法主要围绕它进行；

updater 更新管理中心，与外部通讯，进行事件处理；

selection 选择器，选择合适的交易、输入、转出。

相关方法

receive_tx

/// Receive a transaction, modifying the slate accordingly (which can then be
/// sent back to sender for posting)

create_send_tx

/// Issue a new transaction to the provided sender by spending some of our
/// wallet

complete_tx

/// Complete a transaction as the sender

cancel_tx

/// Rollback outputs associated with a transaction in the wallet

issue_burn_tx

/// Issue a burn tx