docs: def read (self, stream):
        """Reads PCapPacketHeader data from the given stream."""
        self._data = stream.read(self._size)
  
        if len(self._data) >= self._size:
            values = struct.unpack(self._swap + self._format, self._data)
        else:
            values = None, None, None, None
  
        self.ts_sec   = values[0]
        self.ts_usec  = values[1]
        self.incl_len = values[2]
        self.orig_len = values[3]