How to use 'permutation in python without itertools' in Python

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@cython.locals(n=int, i=int, j=int)
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def permutations(iterable):
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    """permutations(range(3), 2) --> (0,1) (0,2) (1,0) (1,2) (2,0) (2,1)"""
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    pool = tuple(iterable)
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    n = len(pool)
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    indices = list(range(n))
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    cycles = list(range(1, n+1))[::-1]
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    yield [ pool[i] for i in indices ]
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    while n:
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        for i in reversed(range(n)):
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            j = cycles[i] - 1
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            if j == 0:
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                indices[i:] = indices[i+1:] + indices[i:i+1]
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                cycles[i] = n - i
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            else:
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                cycles[i] = j
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                indices[i], indices[-j] = indices[-j], indices[i]
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                yield [ pool[i] for i in indices ]
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                break
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        else:
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            return