'Set the size of the pieces in which the content is traded.
The piece size must be a multiple of the chunk size, the unit in which
it is transmitted, which is 16K by default (see
DownloadConfig.set_download_slice_size()). The default is automatic
(value 0).
@param value A number of bytes as per the text.'

def set_piece_length(self, value):

    if (not (isinstance(value, IntType) or isinstance(value, LongType))):
        raise ValueError('Piece    length    not    an    int/long')
    self.input['piece    length'] = value
    self.metainfo_valid = False
