“I’m be nervous, anyway” should be “I’d be nervous, anyway”. Actually, more than nervous, I’d probably be afraid of a 3-meter one, even if it was occupied swallowing my dog. If I could get ahold of a knife or substantial stick, though, I’d do something.
For a reticulated python, that one wasn’t especially large. Wikipedia:
“The reticulated python is the largest snake native to Asia. More than a thousand wild reticulated pythons in southern Sumatra were studied, and estimated to have a length range of 1.5 to 6.5 m (4.9 to 21.3 ft)...”