SequenceDiagram 时序图/序列图

Based on SequenceDiagram.js：http://bramp.github.io/js-sequence-diagrams/

Web Sequence Diagrams Syntax Examples: https://www.websequencediagrams.com/

#### Setting

{
        sequenceDiagram : true
    }

#### Syntax

```seq
    .........
    ```

# or

```sequence
    .........
    ```

#### Examples

```seq
A->B: Message
B->C: Message
C->A: Message
```

```seq
Title: Here is a title
A->B: Normal line
B-->C: Dashed line
C->>D: Open arrow
D-->>A: Dashed open arrow
```

```seq
D->A: text xxxx
A->B: text xxxx
B->A: Wow!
A->D: Hi~
```

```seq
A->A: text
A-->B: text
note right of A: Note Text
```

```seq
# Example of a comment.
Note left of A: Note to the\n left of A
Note right of A: Note to the\n right of A
Note over A: Note over A
Note over A,B: Note over both A and B
```

```seq
participant C
participant B
participant A
Note right of A: By listing the participants\n you can change their order
```

```seq
A->+B: text
B-->A: text
Note right of A: Note A
note over A,B: Note over A-B
```

```sequence
Andrew->China: Says Hello
Note right of China: China thinks\nabout it
China-->Andrew: How are you?
Andrew->>China: I am good thanks!
```