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: handlePlottingOptionArgument.m
    path of file: ./repos/PESTO/private
    
    the code of the file until where you have to start completion: function [ options ] = handlePlottingOptionArgument( options )
    %HANDLEPLOTTINGOPTIONARGUMENT Check argument type or autocreate PestoPlottingOptions
    %from struct (deprecated). Returns a *copy* of the user-provided
    %object (because some plotting routines make changes to the object which are incompatible to other plotting routines).
    

    
function [ options ] = handlePlottingOptionArgument( options )
    %HANDLEPLOTTINGOPTIONARGUMENT Check argument type or autocreate PestoPlottingOptions
    %from struct (deprecated). Returns a *copy* of the user-provided
    %object (because some plotting routines make changes to the object which are incompatible to other plotting routines).
    
    if isa(options, 'PestoPlottingOptions')
        options = options.copy();
    elseif isstruct(options)
        warning('Options argument is not of type PestoPlottingOptions: Initializing PestoPlottingOptions instance from user-provided struct. Make sure all options are set correctly in PestoPlottingOptions(myOptionsStruct).');
        options = PestoPlottingOptions(options);
    else
        error('Options argument is neither of type PestoPlottingOptions nor struct.')
    end