code: def get_next_slip(raw):
      
      if not is_slip(raw):
          return None, raw
      length = raw[1:].index(SLIP_END)
      slip_packet = decode(raw[1:length+1])
      new_raw = raw[length+2:]
      return slip_packet, new_raw
docs: Get the next slip packet from raw data.
  
      Returns the extracted packet plus the raw data with the remaining data stream.