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: mne_read_morph_map.m
    path of file: ./repos/bspm/thirdparty/spm12/external/mne
    
    the code of the file until where you have to start completion: function [leftmap,rightmap] = mne_read_morph_map(from,to,subjects_dir)
%
% [leftmap,rightmap] = mne_read_morph_map(from,to,subjects_dir)
%
% Read the morphing map from subject 'from' to subject 'to'.
% If subjects_dir is not specified, the SUBJECTS_DIR environment
% variable is used
%

%

    
function [leftmap,rightmap] = mne_read_morph_map(from,to,subjects_dir)
%
% [leftmap,rightmap] = mne_read_morph_map(from,to,subjects_dir)
%
% Read the morphing map from subject 'from' to subject 'to'.
% If subjects_dir is not specified, the SUBJECTS_DIR environment
% variable is used
%

%
%   Author : Matti Hamalainen, MGH Martinos Center
%   License : BSD 3-clause
%
%
%   Revision 1.1  2008/03/25 21:06:08  msh
%   Added mne_read_morph_map function
%
%
me='MNE:mne_read_morph_map';

global FIFF;
if isempty(FIFF)
    FIFF = fiff_define_constants();
end