nargin in fuzzy knn

Hello, anyone can help me please. I used fuzzy knn function in matlab, I still wondering why this function use "if nargin<7 then fuzzy=true" because if I delete this code and also the code below this program still running and there's no error. Thankyou

function [hasilDataBaru,jarakKeMasing2Hasil] = FuzzyKNN(contohData, hasilContohData, dataBaru, k, fuzzy)
if nargin<7
    fuzzy = true;
end

jumlahContohData = size(contohData,1);
jumlahDataBaru  = size(dataBaru,1);

m = 2;

maksHasilContohData = max(hasilContohData);
temp = zeros(length(hasilContohData),maksHasilContohData);
for i=1:jumlahContohData
    temp(i,:) = [zeros(1, hasilContohData(i)-1) 1 zeros(1,maksHasilContohData - hasilContohData(i))];
end
hasilContohData = temp;

hasilDataBaru = zeros(jumlahDataBaru, length(k));

jarakKeMasing2Hasil = zeros(jumlahDataBaru, maksHasilContohData, length(k)); 

for i=1:jumlahDataBaru
    jarak = (repmat(dataBaru(i,:), jumlahContohData,1) - contohData).^2;
    jarak = sum(jarak,2)';
    
    [~, idxTerurut] = sort(jarak);

    idxContohDataTerpilih = idxTerurut(1:k);

    bobot = ones(1,length(idxContohDataTerpilih));

    if fuzzy, 
        bobot = jarak(idxContohDataTerpilih).^(-1/(m-1));
        if max(isinf(bobot))
            warning(['Terdapat bobot dengan nilai tak terhingga: ' num2str(i) '. Sehingga nilai bobot dikembalikan menjadi 1.']);
            bobot(isinf(bobot)) = 1;
        end
    end
    
    bobotPerMasing2Hasil = bobot * hasilContohData(idxContohDataTerpilih,:)/(sum(bobot)) ;
    jarakKeMasing2Hasil(i,:) = bobotPerMasing2Hasil;

    [~, idxMaks] = max(bobotPerMasing2Hasil');
    hasilDataBaru(i) = idxMaks;
end