class IntervalTree::Node

def search_s_center(query)
  s_center.select do |k|
    (
      # k is entirely contained within the query
      (k.begin >= query.begin) &&
      (k.end <= query.end)
    ) || (
      # k's start overlaps with the query
      (k.begin >= query.begin) &&
      (k.begin < query.end)
    ) || (
      # k's end overlaps with the query
      (k.end > query.begin) &&
      (k.end <= query.end)
    ) || (
      # k is bigger than the query
      (k.begin < query.begin) &&
      (k.end > query.end)
    )
  end
end