Template:Tree/Subtree

Helper for Template:Tree: apply a template to a string, and then recursively apply this function to each "child", as defined by a function.

• First parameter: Delimiter to prefix future nodes
• current parent: Parent of this subtree
• depth: Depth of parent
• index: i, where parent is the ith child of its parent
• template: Template to apply to each node (first parameter is the node; depth and index are the tree coordinates, 1-based)
• children: Function mapping a parent to children (first parameter is the node; second parameter is the requested index, 1-based; empty result indicates no more children)