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: base64decode.m
    path of file: ./repos/fieldtrip/external/jsonlab
    
    the code of the file until where you have to start completion: function output = base64decode(varargin)
%
% output = base64decode(input)
%
% Decoding a Base64-encoded byte-stream to recover the original data
% This func
    
function is part of JSONLab toolbox (http://iso2mesh.sf.net/cgi-bin/index.cgi?jsonlab)
%

if(nargin==0)
    error('you must provide at least 1 input');
end
if(exist('zmat','file')==2 || exist('zmat','file')==3)
    output=zmat(varargin{1},0,'base64');
    return;
elseif(isoctavemesh)
    error('You must install the ZMat toolbox (http://github.com/fangq/zmat) to use this function in Octave');
end