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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def perm(A, p):
 """ Symmetric permutation of a symmetric sparse matrix. :param A: :py:class:`spmatrix` :param p: :py:class:`matrix` or :class:`list` of length `A.size[0]` """

    assert isinstance(A,spmatrix), "argument must be a sparse matrix"
    assert A.size[0] == A.size[1], "A must be a square matrix"
    assert A.size[0] == len(p), "length of p must be equal to the order of A"
    return A[p,p]