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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 isIdentity(M, tol=1e-06):
 """Check if vtkMatrix4x4 is Identity."""

    for i in [0, 1, 2, 3]:
        for j in [0, 1, 2, 3]:
            e = M.GetElement(i, j)
            if i == j:
                if np.abs(e - 1) > tol:
                    return False
            elif np.abs(e) > tol:
                return False
    return True