def prepare(cls, value, length=0, position=0, is_last_data=True):
        """Prepare Lob header.
        Note that the actual lob data is NOT written here but appended after the parameter block for each row!
        """
        hstruct = WriteLobHeader.header_struct
        lob_option_dataincluded = WriteLobHeader.LOB_OPTION_DATAINCLUDED if length > 0 else 0
        lob_option_lastdata = WriteLobHeader.LOB_OPTION_LASTDATA if is_last_data else 0
        options = lob_option_dataincluded | lob_option_lastdata
        pfield = hstruct.pack(cls.type_code, options, length, position)
        return pfield
Prepare Lob header.
        Note that the actual lob data is NOT written here but appended after the parameter block for each row!