Class SinkTransfer<T>

Terminal destination (sink) — calls a callback on receiving data.

Capabilities: isInput, isPushable

Mechanics:

1. The constructor accepts config.callback: DataHandler
2. push(data) — calls callback(data)
3. destroy() — inherited from BaseStateTransfer, clears _state

Error handling:

• If callback() throws an exception, onError is called.
• With onError provided, the exception is suppressed. Without onError — rethrown.

Configuration (SinkTransferConfig):

• callback: DataHandler — incoming data handler
• onError?: ErrorHandler — error handler
• initialValue?: T — initial value (unused)

Difference from CallbackTransfer (old version):

• The new version inherits from BaseStateTransfer (has _state)
• But _state is not used in push() — data goes directly to callback
• Does not implement isOutput (input only)

Use cases:

• Logging: writing data to console/file
• Side effects: sending metrics, analytics
• Finalization: saving the result to storage