@staticmethod
def _rspiral(width, height):
    """Reversed spiral generator.

        Parameters
        ----------
        width : `int`
            Spiral width.
        height : `int`
            Spiral height.

        Returns
        -------
        `generator` of (`int`, `int`)
            Points.
        """
    x0 = 0
    y0 = 0
    x1 = width - 1
    y1 = height - 1
    while x0 < x1 and y0 < y1:
        for x in range(x0, x1):
            yield x, y0
        for y in range(y0, y1):
            yield x1, y
        for x in range(x1, x0, -1):
            yield x, y1
        for y in range(y1, y0, -1):
            yield x0, y
        x0 += 1
        y0 += 1
        x1 -= 1
        y1 -= 1
    if x0 == x1:
        for y in range(y0, y1 + 1):
            yield x0, y
    elif y0 == y1:
        for x in range(x0, x1 + 1):
            yield x, y0
