Given an integer array nums of length n, construct an array ans of length $2n$ such that ans[i] == nums[i] and ans[i + n] == nums[i] for $0 \leq$ i $<$ n (0-indexed).

In other words, ans is formed by appending nums to itself.

Return the array ans.

Constraints:

• n $==$ nums.length

• $1 \leq$ n $\leq 10^3$ ...