scope

# File activerecord/lib/active_record/associations/association_scope.rb, line 19
      def scope(association, connection)
        klass = association.klass
        reflection = association.reflection
        scope = klass.unscoped
        owner = association.owner
        alias_tracker = AliasTracker.create connection, association.klass.table_name, klass.type_caster
        chain_head, chain_tail = get_chain(reflection, association, alias_tracker)

        scope.extending! Array(reflection.options[:extend])
        add_constraints(scope, owner, klass, reflection, chain_head, chain_tail)
      end