Return the data for the specified column and role

        The column addresses one attribute of the data.

        :param column: the data column
        :type column: int
        :param role: the data role
        :type role: QtCore.Qt.ItemDataRole
        :returns: data depending on the role
        :rtype:
        :raises: None

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

        The column addresses one attribute of the data.

        :param column: the data column
        :type column: int
        :param role: the data role
        :type role: QtCore.Qt.ItemDataRole
        :returns: data depending on the role
        :rtype:
        :raises: None
        """
        return self.columns[column](self._taskfile, role)