old_contents: import socket
  import time
  from collections.abc import MutableSequence
  from pathlib import Path
  
  from robot.board import Board
  from robot.markers import Marker
  
  
  class Camera(Board):
      """
      A camera providing a view of the outside world expressed as ``Marker``s.
      """
  
      def __init__(self, socket_path):
          super().__init__(socket_path)
          self._serial = Path(socket_path).stem
  
      @staticmethod
      def _see_to_results(data):
          """
          Convert the data from ``robotd`` into a sorted of ``Marker``s.
  
          :param data: the data returned from ``robotd``.
          :return: A ``ResultList`` of ``Markers``, sorted by distance from the
                  camera.
          """
          return ResultList(sorted(
              (Marker(x) for x in data["markers"]),
              key=lambda x: x.distance_metres,
          ))
  
      @property
      def serial(self):
          """Serial number of the camera."""
          return self._serial
  
      def see(self):
          """
          Capture and process a new snapshot of the world the camera can see.
  
          Images are captured and processed on-demand in a "blocking" fashion, so
          this method may take a noticeable amount of time to complete its work.
  
          :return: A list of ``Marker`` objects which were identified.
          """
          abort_after = time.time() + 10
  
          self.send({'see': True})
  
          while True:
              try:
                  return self._see_to_results(self.receive(should_retry=True))
              except socket.timeout:
                  if time.time() > abort_after:
                      raise
  
  
  class ResultList(list):
      """
      A ``list`` class with nicer error messages.
  
      In particular, this class provides a slightly better error description when
      accessing indexes and the list is empty.
  
      This is to mitigate a common beginners issue where a list is indexed
      without checking that the list has any items.
      """
  
      def __getitem__(self, *args, **kwargs):
          try:
              return super().__getitem__(*args, **kwargs)
          except IndexError as e:
              if not self:
                  raise IndexError("Trying to index an empty list") from None
              else:
                  raise
  
new_contents: import socket
  import time
  from pathlib import Path
  
  from robot.board import Board
  from robot.markers import Marker
  
  
  class Camera(Board):
      """
      A camera providing a view of the outside world expressed as ``Marker``s.
      """
  
      def __init__(self, socket_path):
          super().__init__(socket_path)
          self._serial = Path(socket_path).stem
  
      @staticmethod
      def _see_to_results(data):
          """
          Convert the data from ``robotd`` into a sorted of ``Marker``s.
  
          :param data: the data returned from ``robotd``.
          :return: A ``ResultList`` of ``Markers``, sorted by distance from the
                  camera.
          """
          return ResultList(sorted(
              (Marker(x) for x in data["markers"]),
              key=lambda x: x.distance_metres,
          ))
  
      @property
      def serial(self):
          """Serial number of the camera."""
          return self._serial
  
      def see(self):
          """
          Capture and process a new snapshot of the world the camera can see.
  
          Images are captured and processed on-demand in a "blocking" fashion, so
          this method may take a noticeable amount of time to complete its work.
  
          :return: A list of ``Marker`` objects which were identified.
          """
          abort_after = time.time() + 10
  
          self.send({'see': True})
  
          while True:
              try:
                  return self._see_to_results(self.receive(should_retry=True))
              except socket.timeout:
                  if time.time() > abort_after:
                      raise
  
  
  class ResultList(list):
      """
      A ``list`` class with nicer error messages.
  
      In particular, this class provides a slightly better error description when
      accessing indexes and the list is empty.
  
      This is to mitigate a common beginners issue where a list is indexed
      without checking that the list has any items.
      """
  
      def __getitem__(self, *args, **kwargs):
          try:
              return super().__getitem__(*args, **kwargs)
          except IndexError as e:
              if not self:
                  raise IndexError("Trying to index an empty list") from None
              else:
                  raise
  
subject: Remove unused import