TWO APPROCHES USING PYTHON3 AND JAVA
\n\n# 1. Solution in Python3 one line code\n\nclass Solution:\n    def getConcatenation(self, nums: List[int]) -> List[int]:\n        return 2*nums \n\n# 2. Sol
\n\n# 1. Solution in Python3 one line code\n```\nclass Solution:\n    def getConcatenation(self, nums: List[int]) -> List[int]:\n        return 2*nums \n```\n# 2. Solution in Java \n```\nclass Solution {\n    public int[] getConcatenation(int[] nums) {\n        int n=nums.length;\n        int answ[]=new int[2*n];\n        for(int i=0;i<n;i++){\n            answ[i]=nums[i];\n            answ[i+n]=nums[i];\n        }\n        return answ;\n    }\n}\n```
['Python3']