def enforce_version_limit!
      limit = version_limit
      return unless limit.is_a? Numeric
      previous_versions = sibling_versions.not_creates.
        order(self.class.timestamp_sort_order("asc"))
      return unless previous_versions.size > limit
      excess_versions = previous_versions - previous_versions.last(limit)
      excess_versions.map(&:destroy)
    end
def enforce_version_limit!
      limit = version_limit
      return unless limit.is_a? Numeric
      previous_versions = sibling_versions.not_creates.
        order(self.class.timestamp_sort_order("asc"))
      return unless previous_versions.size > limit
      excess_versions = previous_versions - previous_versions.last(limit)
      excess_versions.map(&:destroy)
    end
Enforces the `version_limit`, if set. Default: no limit.
 @api private