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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _Aff4Read(aff4_obj, offset, length):
 """Reads contents of given AFF4 file. Args: aff4_obj: An AFF4 stream instance to retrieve contents for. offset: An offset to start the reading from. length: A number of bytes to read. Reads the whole file if 0. Returns: Contents of specified AFF4 stream. Raises: TypeError: If `aff4_obj` is not an instance of AFF4 stream. """

  length = length or (_Aff4Size(aff4_obj) - offset)

  aff4_obj.Seek(offset)
  return aff4_obj.Read(length)