Loads a simple StructuredGrid

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)