#### 系统类图

```mermaid
classDiagram
    class Service {
        +run() Result~JoinHandle~
    }
    <<interface>> Service
    class Pcs {
        +new() Pcs
        +run() Result~JoinHandle~
    }
    class Bms {
        +new() Bms
        +run() Result~JoinHandle~
    }
    Pcs ..|> Service
    Bms ..|> Service
    class Ems {
        +devices: Vec~Service~
        +start_services() Result
    }
    Ems *-- Service
```