### Instruction: For each pair of real numbers $a \ne b$, define the operation $\star$ as \[
(a \star b) = \frac{a + b}{a - b}.
\]What is the value of $((1 \star 2) \star 3)$? Let's program in Python in the response.### Response: def star_operation(a, b):
    return (a + b) / (a - b)

# calculate ((1 star 2) star 3)
result = star_operation(star_operation(1, 2), 3)

print(result)