comefrom: <gouthampradhan>bit_manipulation_GrayCode_1.java
code: public List<Integer> grayCode(int n) {
      List<Integer> result = new ArrayList<>();
      for (int i = 0; i <= ((1 << n) - 1); i++) result.add(i ^ (i >> 1));
      return result;
    }
masked: public List < Integer > var_0 ( int var_1 ) {
    List < Integer > var_2 = new ArrayList < > ( ) ;
    for ( int var_3 = 0 ;
    var_3 <= ( ( 1 << var_1 ) - 1 ) ;
    var_3 ++ ) var_2 . add ( var_3 ^ ( var_3 >> 1 ) ) ;
    return var_2 ;
  }
  