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: base64encode.m
    path of file: ./repos/OpenFace/model_training/AU_training/data extraction/xml_io_tools_2010_11_05
    
    the code of the file until where you have to start completion: function y = base64encode(x, alg, isChunked, url_safe)
%BASE64ENCODE Perform base64 encoding on a string.
% INPUT:
%   x    - block of data to be encoded.  Can be a string or a numeric
%          vector containing integers in the range 0-255.
%   alg  - Algorithm to use: can take values 'java' or 'matlab'. Optional
%          variable defaulting to 'java' which is a little faster. If
%          'java' is chosen than core of the code is performed by a call to
%          a java library. Optionally all operations can be performed using
%          matleb code.
%   isChunked - encode output into 76 character blocks. The returned 
%          encoded string is broken into lines of no more than
%          76 characters each,
    
function may be used to encode strings into the Base64 encoding
%   specified in RFC 2045 - MIME (Multipurpose Internet Mail Extensions).  
%   The Base64 encoding is designed to represent arbitrary sequences of 
%   octets in a form that need not be humanly readable.  A 65-character 
%   subset ([A-Za-z0-9+/=]) of US-ASCII is used, enabling 6 bits to be 
%   represented per printable character.
%
%   See also BASE64DECODE.
%
%   Written by Jarek Tuszynski, SAIC, jaroslaw.w.tuszynski_at_saic.com
%
%   Matlab version based on 2004 code by Peter J. Acklam
%   E-mail:      pjacklam@online.no
%   URL:         http://home.online.no/~pjacklam
%   http://home.online.no/~pjacklam/matlab/software/util/datautil/base64encode.m

if nargin<2, alg='java';      end
if nargin<3, isChunked=false; end
if ~islogical(isChunked) 
  if isnumeric(isChunked)
    isChunked=(isChunked>0);
  else
    isChunked=false;
  end 
end
if nargin<4, url_safe=false; end
if ~islogical(url_safe) 
  if isnumeric(url_safe)
    url_safe=(url_safe>0);
  else
    url_safe=false;
  end 
end


%% if x happen to be a filename than read the file
if (numel(x)<256)
  if (exist(x, 'file')==2)
    fid = fopen(x,'rb');
    x = fread(fid, 'uint8');             % read image file as a raw binary
    fclose(fid);
  end