code: def _extract_packet_bytes(self) -> Optional[bytes]:
      # Do we have enough data to read the header?
      start_offset = self.HEADLEN
      if self._buffer.length >= start_offset:
          header = self._buffer.peek(0, start_offset)
          fields = struct.unpack("<BI", header)
          magic, dlength = fields
          assert magic == ord("W")
          # Do we have enough data to read the full record?
          end_offset = self.HEADLEN + dlength
          if self._buffer.length >= end_offset:
              rec_data = self._buffer.get(start_offset, end_offset)
              return rec_data
      return None
  
imports: import socket
  import struct
  import threading
  import time
  import uuid
  from typing import TYPE_CHECKING, Any, List, Optional
  from wandb.proto import wandb_server_pb2
  from .None import tracelog
label_desc: Use image node_id 15 for calling the SockClient obj's underlying member method code with example usage: obj._extract_packet_bytes() and returns: None, rec_data