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What is this supposed to be plugged into

2007 Pontiac Grand Prix gt 3.8
Doing spark plugs and noticed this wasn’t plugged in. The one right next to it is plugged into a hose but there is nothing I can find that this should go into

The one with the hose is the MAP Sensor.
The one without the hose is the Barometric Pressure (BARO) Sensor. It doesn’t get a hose. It’s just open to the atmosphere.