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: add_element.m
    path of file: ./repos/MatlabGDSPhotonicsToolbox/Functions/GDSII Library/Basic/@gds_structure
    
    the code of the file until where you have to start completion: function [ostruc] = add_element(istruc, gelm);
%function [ostruc] = add_element(istruc, gelm);

    
function [ostruc] = add_element(istruc, gelm);
%function [ostruc] = add_element(istruc, gelm);
%
% Add elements or other structures to structures
%
% istruc :   a gds_structure object
% gelm :     a gds_element object or a cell array of gds_element
%            objects
% ostruc :   gds_structure containing the new elements or structure
%

% Initial version, Ulf Griesmann, December 2011

% copy input to output
ostruc = istruc;

% and add the new element
if isa(gelm, 'gds_element');
   ostruc.el{end