@Override
	public VarKeyRecordNode getLeftmostLeafNode() throws IOException {
		VarKeyNode node = nodeMgr.getVarKeyNode(getBufferId(0));
		return node.getLeftmostLeafNode();
	}
Split this interior node and insert new child entry (key and buffer ID).  
Assumes 3 or more child keys exist in this node.
@param newKey new child key 
@param newId new child node's buffer ID
@param node child node instance (corresponds to newKey and newId)
@return root node.
@throws IOException thrown if IO error occurs
Ghidra/Framework/DB/src/main/java/db/VarKeyInteriorNode.java