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: deislands3d.m
    path of file: ./repos/iso2mesh
    
    the code of the file until where you have to start completion: function cleanimg=deislands3d(img,sizelim)
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% cleanimg=deislands3d(img,sizelim)
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% remove isolated islands for 3D image (for each slice)
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% author: Qianqian Fang, <q.fang at neu.edu>
%
% input:
%      img: a 3D volumetric image
%      sizelim: maximum island size (in pixels) for each x/y/z slice
%

    
function cleanimg=deislands3d(img,sizelim)
%
% cleanimg=deislands3d(img,sizelim)
%
% remove isolated islands for 3D image (for each slice)
%
% author: Qianqian Fang, <q.fang at neu.edu>
%
% input:
%      img: a 3D volumetric image
%      sizelim: maximum island size (in pixels) for each x/y/z slice
%
% output:
%      cleanimg: 3D image after removing the islands
%
% -- this function is part of iso2mesh toolbox (http://iso2mesh.sf.net)
%

maxisland=-1;
if(nargin==2) maxisland=sizelim; end