I have found the above causes a problem with OPC generation. If I define a OP i.e. -o in the command line, I have fond the EoR creates and OPC using this value as if it isn't been passed in. I hacked the lib in my version, this is just a note for others. I edited the declaration and remove the assignment =0 i.e. def calc_opc_hex(self, k_hex, op_hex): ...
Hope it helps.
BR
Jerry