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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 _K(m):
 """ matrix K_m from Wiktorsson2001 """

    M = m*(m - 1)//2
    K = np.zeros((M, m**2), dtype=np.int64)
    row = 0
    for j in range(1, m):
        col = (j - 1)*m + j
        s = m - j
        K[row:(row+s), col:(col+s)] = np.eye(s)
        row += s
    return K