You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: DataIO.m
    path of file: ./repos/VINS/libraries/@DataIO
    
    the code of the file until where you have to start completion: %{
    This class creates a 'nan' variable of given dimensions
    
function to mainly store/retrieve data in a std.
    fashion.
%}

classdef DataIO < handle
    properties (Access = private)
        data
        vec_len
        num_readings
        index
    end
    
    methods        
        %% Constructor
        function obj = DataIO(vec_len, num_readings)           
            obj.vec_len = vec_len;            
            obj.num_readings = num_readings;

            obj.clear();
        end