Createa a polygonal disk with a hole in the center. The disk has zero
    height. The user can specify the inner and outer radius of the disk, and
    the radial and circumferential resolution of the polygonal representation.

    Parameters
    ----------
    center : np.ndarray or list
        Center in [x, y, z]. middle of the axis of the polygon.

    radius : float
        The radius of the polygon

    normal : np.ndarray or list
        direction vector in [x, y, z]. orientation vector of the cone.

    n_sides : int
        Number of sides of the polygon

def Polygon(center=(0.,0.,0.), radius=1, normal=(0,0,1), n_sides=6):
    """
    Createa a polygonal disk with a hole in the center. The disk has zero
    height. The user can specify the inner and outer radius of the disk, and
    the radial and circumferential resolution of the polygonal representation.

    Parameters
    ----------
    center : np.ndarray or list
        Center in [x, y, z]. middle of the axis of the polygon.

    radius : float
        The radius of the polygon

    normal : np.ndarray or list
        direction vector in [x, y, z]. orientation vector of the cone.

    n_sides : int
        Number of sides of the polygon
    """
    src = vtk.vtkRegularPolygonSource()
    src.SetCenter(center)
    src.SetNumberOfSides(n_sides)
    src.SetRadius(radius)
    src.SetNormal(normal)
    src.Update()
    return vtki.wrap(src.GetOutput())