An instance of VirtualRoot is a hidden root that “owns” the actual roots. It’s only here so we can use the same code for real roots and children. Otherwise we have to write special code for the top level parents. Note: This is very different from the concept of virtual roots in better_nested_set which is the equivalent of .root.children to get the immediate children of a top level root

# File lib/acts_as_hausdorff_space.rb, line 50
    def initialize( left_val,right_val)
     self.left_col_val = left_val
     self.right_col_val = right_val
     @children = HSArray.new
     @children.parent = self
    end