def METHOD_NAME(self) -> None:
    """Initializes the Frame's border & corner chars from the content property."""
    top, _, bottom = self.descriptor
    top_left, top_right = self._get_corners(top)
    bottom_left, bottom_right = self._get_corners(bottom)
    self.borders = list(self._get_borders(self.descriptor))
    self.corners = [
        top_left,
        top_right,
        bottom_right,
        bottom_left,
    ]