Matching Sums

Bob's machine and Alice's machine each draw two integers uniformly and independently from ${1,2,\dots,10}$ and report the sum of the pair. The script computes the probability that the two reported sums are equal.

from collections import Counter
from itertools import product

counts = Counter(a + b for a, b in product(range(1, 11), repeat=2))
total = sum(counts.values())                      # 100 equally likely pairs
collision = sum((c / total) ** 2 for c in counts.values())
print(round(collision, 3))

What does it print?

Answer format: round to 3 decimal places.