code: def unpack(self, fmt, length=1):
          
          try:
              info = struct.unpack(fmt, self.stream.read(length))[0]
          except struct.error as e:
              raise SDKException(ErrorCode.unpack_error(e.args[0]))
          return info
docs: Unpack the stream contents according to the specified format in `fmt`.
          For more information about the `fmt` format see: https://docs.python.org/3/library/struct.html
  
          Args:
              fmt (str): format string.
              length (int): amount of bytes to read.
  
          Returns:
              variable: the result according to the specified format.