:conditions => [ "visible = ? AND member_type='Node' and member_id=? ", true, self.id])
raise OSM::APIPreconditionFailedError.new("Node #{self.id} is still used by relation #{rel.relation.id}.") unless rel.nil?
:conditions => [ "visible = ? AND member_type='Node' and member_id=? ", true, self.id])
raise OSM::APIPreconditionFailedError.new("Node #{self.id} is still used by relation #{rel.relation.id}.") unless rel.nil?