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: CBIG_CreateLooseGCAHeadMask.m
    path of file: ./repos/CBIG/utilities/matlab/vol
    
    the code of the file until where you have to start completion: function CBIG_CreateLooseGCAHeadMask(input_file, output_file, dist)

% Create loose GCA head mask. This function 1) set nonzero value to 1; 2)
% dilate the mask; 3) fill in the holes
%

    
function CBIG_CreateLooseGCAHeadMask(input_file, output_file, dist)

% Create loose GCA head mask. This function 1) set nonzero value to 1; 2)
% dilate the mask; 3) fill in the holes
%
%   CBIG_CreateLooseGCAHeadMask(input_file, output_file, dist)
%   Input:
%       input_file  : input mri nifti file
%       output_file : output mri nifti file
%       dist        : dilate how many voxels
%
% Written by CBIG under MIT license: https://github.com/ThomasYeoLab/CBIG/blob/master/LICENSE.md


if(ischar(dist))
   dist = str2num(dist); 
end