sequenceDiagram
    Alice->>Bob: Step 1
    Bob->>Charlie: Step 2
    Charlie-->>Alice: Done
---
+-------+     +-----+     +---------+
| Alice |     | Bob |     | Charlie |
+---+---+     +--+--+     +----+----+
    |            |             |
    | Step 1     |             |
    +----------->|             |
    |            |             |
    |            | Step 2      |
    |            +------------>|
    |            |             |
    | Done       |             |
    |<.........................+
    |            |             |
