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: spm_clusters.m
    path of file: ./repos/malini/Codes/deconvolution - model/spm8
    
    the code of the file until where you have to start completion: function A = spm_clusters(L)
% Return the cluster index for a point list

    
function A = spm_clusters(L)
% Return the cluster index for a point list
% FORMAT [A] = spm_clusters(L)
% L     - locations [x y x]' {in voxels} ([3 x m] matrix)
%
% A     - cluster index or region number ([1 x m] vector)
%__________________________________________________________________________
%
% spm_clusters characterizes a point list of voxel values defined with
% their locations (L) in terms of edge, face and vertex connected
% subsets, returning a list of indices in A, such that the ith location
% belongs to cluster A(i) (using an 18 connectivity scheme).
%__________________________________________________________________________
% Copyright (C) 2008 Wellcome Trust Centre for Neuroimaging

% Jesper Andersson
% $Id: spm_clusters.m 3822 2010-04-16 18:43:08Z karl $


if isempty(L), A = []; return; end