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: cluster_find_index.m
    path of file: ./repos/CanlabCore/CanlabCore/Cluster_contig_region_tools
    
    the code of the file until where you have to start completion: function [wh_cluster, min_distance] = cluster_find_index(cl, varargin)
% Ever see an interesting blob when visualizing a clusters structure, but
% don't know which index number in the clusters structure vector it
% corresponds to?
%
% With this function, find the index number of the closest cluster to one you specify
% graphically by clicking on.
%
% :Usage:
% ::
%

    
function [wh_cluster, min_distance] = cluster_find_index(cl, varargin)
% Ever see an interesting blob when visualizing a clusters structure, but
% don't know which index number in the clusters structure vector it
% corresponds to?
%
% With this function, find the index number of the closest cluster to one you specify
% graphically by clicking on.
%
% :Usage:
% ::
%
%    function [wh_cluster, min_distance] = cluster_find_index(cl, [keep display flag, 1/0])
%
keepdisplay = 0;
if length(varargin) > 0
    keepdisplay = varargin{1};
end