@classmethod
def vline(cls, x=None, y=None, char='|', n=None):
    """
        Insert a vertical line at position, at most n characters or height of
        window.

        :param x: optional x value
        :param y: optional y value
        :param char: the character to print, default '|'
        :param n: the number of characters, default rest of height of window
        """
    x, y = cls._fix_xy(x, y)
    n = cls.HEIGHT if n is None else n
    return cls.WINDOW.vline(y, x, char, n)
