Use a numeralogical technique known to teens from the '80s to predict the love percentage from names

LoveCalculator.py

#!/usr/bin/env python3
#Use: LoveCalculator.py "Katy Perry" "Justin Bieber"

import sys
import itertools
def pairwise(iterable):
    "s -> (s0,s1), (s1,s2), (s2, s3), ..."
    a, b = itertools.tee(iterable)
    next(b, None)
    return zip(a, b)

def sumline(n):
    """Add pairs of digits in a string of digits.
    So "22" -> "4"
       "67" -> "13"
       "123" -> "25"
       "456" -> "911"
    """
    result=""
    for (a,b) in pairwise(n):
        result += str(int(a)+int(b))
    return result

name1 = sys.argv[1]
name2 = sys.argv[2]
names = name1 + name2

numberstring = ("".join([str(names.lower().count(k)) for k in 'loves'])) 
print("LOVES")
while len(numberstring)>2:
    print(numberstring)
    numberstring = sumline(numberstring)
print(name1, "loves", name2, numberstring+'%')