Method to return all the boundary points in sorted order.

[ShivKJ]

Hi,
I would be nice if there is a function which returns a sorted Set of all the interval's end points. I found variable boundary_table but it not exposed in API.

Could you add a property which return this.
Something like the following

@property
def boundary_points(self) -> SortedSet:
    """
    :return: a sorted set consisting of end point of all the interval
             present in the interval tree
    """
    return SortedSet(self.boundary_table)