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_data_id.m
    path of file: ./repos/bspm/thirdparty/spm12
    
    the code of the file until where you have to start completion: function ID = spm_data_id(varargin)
% generates a specific real number in a deterministic way
% from any data structure
% FORMAT ID = spm_data_id(X);
% X  - numeric, character, cell or stucture array[s]

    
function ID = spm_data_id(varargin)
% generates a specific real number in a deterministic way
% from any data structure
% FORMAT ID = spm_data_id(X);
% X  - numeric, character, cell or stucture array[s]
% ID - specific ID
%__________________________________________________________________________
% Copyright (C) 2009 Wellcome Trust Centre for Neuroimaging

% Vladimir Litvak (based on Karl's spm_vec)
% $Id: spm_data_id.m 6712 2016-02-04 15:12:25Z peter $

X     = varargin;

if length(X) == 1
    X = X{1};
end