" in" appears 25 times on the page to be exact, with 16 of those being in the table of contents and 9 being in the text afterwards.
“in” appears 54 times, as you know end up hitting “string” and so on.
Had I known that the functions table of contents was as short as it is I would probably have just scrolled.
Info that could help others help you:
House or flat?
Renting or owning?
How large an area do you need to heat?
How many rooms?
Temperature and savings:
Where I live they say that a house with people living in it should be at least 16°C (~60°F) to handle the moisture we generate.
Humans should have at least 18°C (64°F), preferably 20°C (68°F).
That means that you could close doors and let unoccupied rooms have lower temperature than the rooms you use.
If you’re stuck with space heaters then you’ll save quite a lot that way.