Speaking of py, I'm learning a bit of sushimancy.
I've got a surplus of both syngas and acetylene, and I'm just dumping the excess in my glassworks. Only issue is I don't have enough of either to keep the working at all times. I've got a steady stream of gasoline coming but if I dumped it in the glassworks it'd take priority, and I'm storing it in a tailings pond so I can't use an overflow valve. So what I'm doing here is prioritizing syngas (since there's always an excess) with a check valve and since I haven't unlocked combinators yet I'm making sure to use two pumps to use as a gate. One checks for the valve to see if there's less than 5% syngas in the overflow system, in which case it locks a portion of pipe. The other exists as a way not to backflow into the first pump to create a portion of gasoline that's can be partitioned from the rest of the pipeline. So syngas takes priority, is consumed first, and if there's no more syngas in the system, the sluice is unlocked and it lets the gasoline through until there's a backlog of syngas again. I've timed it and it seems that 5% is more than enough not to fully load the overflow pipe with backed up syngas: 10% works too but it gets >90% full and I'd rather not test it.
The second pump also adds as a secondary gate whenever there's acetylene: when there is at least 1 unit of acetylene in the check valve, it stops pumping, holding the gasoline back.

I should have just voided both acetylene and syngas and used just the gasoline but still, it makes me feel smart