def METHOD_NAME(self, e):
    r"""Starts a variable drag operation.
    Parameters
    ----------
    e : QMousePressEvent
    """
    item = self.ui.table_variables.itemAt(e.pos())
    if item is None:
        return
    row = self.ui.table_variables.row(item)
    var = self.ui.table_variables.item(row, 0).text()
    drag_and_drop.send(self.ui.table_variables, var)