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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 load_structured():
 """ Loads a simple StructuredGrid """

    x = np.arange(-10, 10, 0.25)
    y = np.arange(-10, 10, 0.25)
    x, y = np.meshgrid(x, y)
    r = np.sqrt(x**2 + y**2)
    z = np.sin(r)
    return vtki.StructuredGrid(x, y, z)