Task: Program Execution
Input (English): U, 2, 7, x, u, C, 4
Output (English): [['U', '2', '7', 'x', 'u', 'C'], ['U', '2', '7', 'x', 'u', '4'], ['U', '2', '7', 'x', 'C', '4'], ['U', '2', '7', 'u', 'C', '4'], ['U', '2', 'x', 'u', 'C', '4'], ['U', '7', 'x', 'u', 'C', '4'], ['2', '7', 'x', 'u', 'C', '4']]