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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 create_horizontal_plane():
    '''
    Creates a horizontal plane.
    '''
    v = np.array([
        [1., 0., 0.],
        [-1., 0., 0.],
        [0., 0., 1.],
        [0., 0., -1.]
    ])
    f = [[0, 1, 2], [3, 1, 0]]
    return Mesh(v=v, f=f)