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: mahaleeg.m
    path of file: ./repos/erplab/functions
    
    the code of the file until where you have to start completion: % Usage
%
% >> d = mahaleeg(ch1,ch2);
% >> d = mahaleeg(ch)
%
% d = mahaleeg(ch1,ch2) computes the Mahalanobis distance (in squared units) of each samp
    
function was made to work with ERPLAB channel operations
%
% See mahal.m
%
%
% Author: Javier Lopez-Calderon

function  d = mahaleeg(ch1,ch2, nsweep)

d=[];

if nargin<1
        help mahaleeg
        return
end