Express the range using roster notation.

I know that P(A) = {empty set, {1}, {2}, {3}, {1,2}, {1,3}, {2,3}, {1,2,3}}. What do I do next? How do I apply P(A) to "X u {1}"? Pleas explain each step clearly. Don't just provide the answer.

Let A = {1,2,3} f: P(A) + P(A). For X S A, f(x) = X u {1}