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_RF_propagate_in_vol.m
    path of file: ./repos/CBIG/stable_projects/registration/Wu2017_RegistrationFusion/freesurfer_baseline/utilities
    
    the code of the file until where you have to start completion: function [output, output_seg] = CBIG_RF_propagate_in_vol(input_lh, input_rh, mask_input)
% CBIG_RF_propagate_in_vol(input_lh, input_rh, mask_input)
%
% This function grows a volume (e.g. segmentation labels) to fill up an input mask
%
% Input:
%     - input_lh  :
%                   path to input volume in left hemisphere
%     - input_rh  :
%                   path to input volume in right hemisphere
%     - mask_input:
%                   path to the input mask which defines regions to be filled 
%                   (e.g. a liberal cortical mask)
%                   (default: $CBIG_CODE_DIR/bin/liberal_cortex_masks/
%                     MNI152_norm_cortex_estimate.nii.gz)
%

    
function [output, output_seg] = CBIG_RF_propagate_in_vol(input_lh, input_rh, mask_input)
% CBIG_RF_propagate_in_vol(input_lh, input_rh, mask_input)
%
% This function grows a volume (e.g. segmentation labels) to fill up an input mask
%
% Input:
%     - input_lh  :
%                   path to input volume in left hemisphere
%     - input_rh  :
%                   path to input volume in right hemisphere
%     - mask_input:
%                   path to the input mask which defines regions to be filled 
%                   (e.g. a liberal cortical mask)
%                   (default: $CBIG_CODE_DIR/bin/liberal_cortex_masks/
%                     MNI152_norm_cortex_estimate.nii.gz)
%
% Output:
%     - output    :
%                   output volume after resolving midline issues 
%                   (no propagation)
%     - output_seg:
%                   propagated output volume in segmentation format and masked
%                   (rh values have a base of 1000)
%
% Example:
% [output, output_seg] = CBIG_RF_propagate_in_vol('lh.fsaverage2MNI_annot.nii.gz', 
%                 'rh.fsaverage2MNI_annot.nii.gz', 'MNI_cortex_estimate.nii.gz')
% This command takes in the two input volumes and returns the output by removing data in the midline voxels. 
% The volume will then be propagated to fill the MNI cortex mask. 
% The sementation formatted volume output of this propagated volume is then returned as output_seg.
%
% Written by Wu Jianxiao and CBIG under MIT license: https://github.com/ThomasYeoLab/CBIG/blob/master/LICENSE.md

%Function usage
if nargin < 2
    disp('usage: CBIG_RF_propagate_in_vol(input_lh, input_rh, mask_input');
    return
end