Navigate from a node to its first child or return Option.none if the zipper is focused on a leaf.
Option.none
See head for an unsafe version.
This is like rewind in that both take you to the forest head but this will also descend one level.
The underlying type of the tree.
An updated zipper pointing at a new focus or Option.none() if there is no first child.
Option.none()
Navigate from a node to its first child or return
Option.noneif the zipper is focused on a leaf.See head for an unsafe version.
This is like rewind in that both take you to the forest head but this will also descend one level.