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: cellcovold.m
    path of file: ./repos/fieldtrip/external/cellfunction
    
    the code of the file until where you have to start completion: function [c] = cellcov(x, y, dim, flag)

% [C] = CELLCOV(X, DIM) computes the covariance, across all cells in x along 
% the dimension dim. When there are three inputs, covariance is computed between
% all cells in x and y
% 
% X (and Y) should be linear cell-array(s) of matrices for which the size in at 

    
function [c] = cellcov(x, y, dim, flag)

% [C] = CELLCOV(X, DIM) computes the covariance, across all cells in x along 
% the dimension dim. When there are three inputs, covariance is computed between
% all cells in x and y
% 
% X (and Y) should be linear cell-array(s) of matrices for which the size in at 
% least one of the dimensions should be the same for all cells 


if nargin<4 && iscell(y)
  flag = 1;
elseif nargin<4 && isnumeric(y)
  flag = dim;
end