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: InputFemFilePrinter.m
    path of file: ./repos/Swan/PostProcess/Printer/FreeFem
    
    the code of the file until where you have to start completion: classdef InputFemFilePrinter < FilePrinter
    
    properties (Access = private)
        connectivities
        coordinates
        isElemInThisSet

    
function printMaterialSets(obj)
            iD = obj.fileID;
            fprintf(iD,'\n');            
            fprintf(iD,'MaterialSets = [\n');
            printFormat = [repmat('%12.0d ',1,2),'\n'];
            for imatSet = 1:numel(obj.isElemInThisSet)
                elemSet = obj.isElemInThisSet{imatSet};
                n       = length(elemSet);
                toPrint = [elemSet';imatSet*ones(1,n)];
                fprintf(iD,printFormat,toPrint);
            end