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: spm_create_vol.m
    path of file: ./repos/spm12
    
    the code of the file until where you have to start completion: function V = spm_create_vol(V)
% Create a NIfTI image volume
% FORMAT V = spm_create_vol(V)
% V        - image volume information (see spm_vol.m)

    
function V = spm_create_vol(V)
% Create a NIfTI image volume
% FORMAT V = spm_create_vol(V)
% V        - image volume information (see spm_vol.m)
%__________________________________________________________________________
% Copyright (C) 2005-2018 Wellcome Trust Centre for Neuroimaging

% John Ashburner
% $Id: spm_create_vol.m 7455 2018-10-22 12:34:12Z guillaume $


if ~isstruct(V)
    error('Input argument V is not a structure.');
end