Function merge_subtrees_non_root

pub fn merge_subtrees_non_root(
    left_child: &ChainingValue,
    right_child: &ChainingValue,
    mode: Mode<'_>,
) -> ChainingValue

Compute a non-root parent node chaining value from two child chaining values.

See the module level examples, particularly the discussion of valid tree structures. The left and right child chaining values can come from either Hasher::finalize_non_root or other calls to merge_subtrees_non_root. “Chaining value” is the academic term for a non-root or non-final hash.