Return the data for the specified column and role

        For DisplayRole the element in the list will be converted to a sting and returned.

        :param column: the data column
        :type column: int
        :param role: the data role
        :type role: QtCore.Qt.ItemDataRole
        :returns: data depending on the role, or None if the column is out of range
        :rtype: depending on the role or None
        :raises: None

def data(self, column, role):
        """Return the data for the specified column and role

        For DisplayRole the element in the list will be converted to a sting and returned.

        :param column: the data column
        :type column: int
        :param role: the data role
        :type role: QtCore.Qt.ItemDataRole
        :returns: data depending on the role, or None if the column is out of range
        :rtype: depending on the role or None
        :raises: None
        """
        if role == QtCore.Qt.DisplayRole:
            if column >= 0 and column < len(self._list):
                return str(self._list[column])