def match_path( ypath_str )
            depth = 0
            matches = []
            YPath.each_path( ypath_str ) do |ypath|
                seg = match_segment( ypath, 0 )
                matches += seg if seg
            end
            matches.uniq
        end
def match_path( ypath_str )
            depth = 0
            matches = []
            YPath.each_path( ypath_str ) do |ypath|
                seg = match_segment( ypath, 0 )
                matches += seg if seg
            end
            matches.uniq
        end
YPath search returning a complete depth array