human
I am working on the file "House Investment Return.ipynb".
The first task is:
Note that there are cases where there is no IRR. Your investment loses money, even assuming your upfront dollars are valued equally to later hypothetical dollars. It cannot grow your wealth.
There will be cases where this happens with our house investment.
We can model this "investment" by subtracting the rent we're not paying from the other costs that we now must pay. Now, (drumroll please), let's look at the IRR for our hypothetical house, depending on how long we stay in it:
Can you write Python code for it?
assistant
#Here is the Python code you requested.

for year in xrange(1, 16):
    def dcf(r_i): return buy(r_i / 12, 12 * year) - rent(r_i / 12, 12 * year)
    print year, irr(dcf)