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: AddOptions.m
    path of file: ./repos/MatlabGDSPhotonicsToolbox/Functions/Utils/Data validation & formatting
    
    the code of the file until where you have to start completion: function structure = AddOptions(structure, varargin)
%ADDOPTIONS is a general function that reads the varargin standard matlab format of
% argument pairs: 'string', value.
%
%     This uses an input structure that defines the options handled as well as the
%     default values for those options. In AddOptions, a field that does not exist

    
function structure = AddOptions(structure, varargin)
%ADDOPTIONS is a general function that reads the varargin standard matlab format of
% argument pairs: 'string', value.
%
%     This uses an input structure that defines the options handled as well as the
%     default values for those options. In AddOptions, a field that does not exist
%     is created contrary to ReadOptions.
%
%     Example: function structure = CreateStructure(varargin)
%                structure = struct('invert', true, 'rotate', 90);
%                structure = ReadOptions(structure, varargin{:});
%              end