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_pairwise.m
    path of file: ./repos/spm12/toolbox/Longitudinal
    
    the code of the file until where you have to start completion: function out = spm_pairwise(job)
% Longitudinal registration of image pairs
% FORMAT out = spm_pairwise(job)

    
function out = spm_pairwise(job)
% Longitudinal registration of image pairs
% FORMAT out = spm_pairwise(job)
% See tbx_cfg_longitudinal.m for a description of the various fields. 
%__________________________________________________________________________
% Copyright (C) 2012-2019 Wellcome Trust Centre for Neuroimaging

% John Ashburner
% $Id: spm_pairwise.m 7563 2019-04-01 10:39:24Z guillaume $


N = numel(job.vols1);
if numel(job.vols2) ~= N, error('Incompatible numbers of scans.'); end