Type Alias Visitor<State>

A visitor function that is called for each element in the envelope.

The visitor function takes the following parameters:

• envelope: The current envelope element being visited
• level: The depth level in the hierarchy (0 for root)
• incomingEdge: The type of edge connecting this element to its parent
• state: Optional context passed down from the parent's visitor call

The visitor returns a tuple of:

• The state that will be passed to child elements
• A boolean indicating whether to stop traversal (true = stop)

This enables accumulating state or passing context during traversal.