@Override
	public boolean hasPreviousLeaf() throws IOException {
		int prevLeafId = buffer.getInt(PREV_LEAF_ID_OFFSET);
		return (prevLeafId >= 0);
	}
Get the key offset within the node's data buffer
@param index key/record index
@return positive record offset within buffer
Ghidra/Framework/DB/src/main/java/db/FixedKeyRecordNode.java