code: def select_whole_line(self, line=None, apply_selection=True):
          
          if line is None:
              line = self.current_line_nbr()
          return self.select_lines(line, line, apply_selection=apply_selection)
docs: Selects an entire line.
  
          :param line: Line to select. If None, the current line will be selected
          :param apply_selection: True to apply selection on the text editor
              widget, False to just return the text cursor without setting it
              on the editor.
          :return: QTextCursor