Model's flags method

[Higgs]

Hi. I'm reading official Qt documentation and I can't understant piece of code:

//! [quoting mymodel_f]
Qt::ItemFlags MyModel::flags(const QModelIndex &index) const
{
    return Qt::ItemIsEditable | QAbstractTableModel::flags(index);
}
//! [quoting mymodel_f]

//! [quoting mymodel_f]
Qt::ItemFlags MyModel::flags(const QModelIndex &index) const
{
    return Qt::ItemIsEditable | QAbstractTableModel::flags(index);
}
//! [quoting mymodel_f]

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Qt::ItemIsEditable | QAbstractTableModel::flags(index);

Qt::ItemIsEditable | QAbstractTableModel::flags(index);

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Why we can't just return Qt::ItemIsEditable?