python cursor.callproc() function not calling procedure

Question

New(ish) to SQL, just discovered stored procedures.

Restructuring a monolithic Python 3.7 script.

Here's my stored procedure:

CREATE PROCEDURE domSel(IN xip VARCHAR(16))
BEGIN
SELECT domain FROM pytest.nodes2 WHERE ip = xip
END;

It selects a domain based off an IP. The original code snippet in Python looks like this:

    for i,x,y in ip_ll:
        cursorA.execute("SELECT domain FROM pytest.nodes2 WHERE ip = '" + str(i) + "'")
        hosts_low.append(cursorA.fetchone())
        ips_low_latency.append(i)
        lat_low.append(x)

The following line is supposed to be the replacement:

# The #s are of course the IP address.
result_arg = cursorA.callproc('domSel', args=('###.##.###.###,))
print(result_arg[1])

But it's giving me the error:

Traceback (most recent call last):
  File "./2queryMagic.py", line 45, in <module>
    print(result_arg[1])
IndexError: tuple index out of range

I tried to print arg[0], but of course that's the argument name. I tried iterating over the results in a for loop, this didn't work either... Python doesn't seem to be calling the procedure. Hopefully this is enough information, banging my head off the desk atm.

Answer 1

As per rdas' comment, precedures require an out variable, and they must be referenced with @var_name

call domSel('###.##.###.###', @dom);

(worked, but ofc relayed the actual domain)
+-------------------+
| domain            |
+-------------------+
| -domain.com      -|
+-------------------+