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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 roty(t):
 """Rotation about the y-axis."""

    c = np.cos(t)
    s = np.sin(t)
    return np.array([[c,  0,  s],
                     [0,  1,  0],
                     [-s, 0,  c]])