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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 levenshtein(x, y):
 """Levenshtein edit distance :param x: :param y: strings :returns: distance :complexity: `O(|x|*|y|)` """

    n = len(x)
    m = len(y)
    #                         initializing row 0 and column 0
    A = [[i + j for j in range(m + 1)] for i in range(n + 1)]
    for i in range(n):
        for j in range(m):
            A[i + 1][j + 1] = min(A[i][j + 1] + 1,              # insert
                                  A[i + 1][j] + 1,              # delete
                                  A[i][j] + int(x[i] != y[j]))  # subst.
    return A[n][m]