Streams chunks of a given file starting at given offset.

    Args:
      filedesc: A `file` object to stream.
      offset: An integer offset at which the file stream should start on.
      amount: An upper bound on number of bytes to read.

    Returns:
      Generator over `Chunk` instances.

def StreamFile(self, filedesc, offset=0, amount=None):
    """Streams chunks of a given file starting at given offset.

    Args:
      filedesc: A `file` object to stream.
      offset: An integer offset at which the file stream should start on.
      amount: An upper bound on number of bytes to read.

    Returns:
      Generator over `Chunk` instances.
    """
    reader = FileReader(filedesc, offset=offset)
    return self.Stream(reader, amount=amount)