code: def get_chessboard(self, columns, rows, show=False):
          
          found_chessboard = [False, False]
          while not all(found_chessboard):
              frames = self.get_frames()
              if show:
                  self.show_frames(1)
              for i, frame in enumerate(frames):
                  (found_chessboard[i],
                   corners) = cv2.findChessboardCorners(frame, (columns, rows),
                                                    flags=cv2.CALIB_CB_FAST_CHECK)
          return frames
docs: Take a picture with a chessboard visible in both captures.
  
          ``columns`` and ``rows`` should be the number of inside corners in the
          chessboard's columns and rows. ``show`` determines whether the frames
          are shown while the cameras search for a chessboard.