set_inverse_instance

# File activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb, line 43
        def set_inverse_instance(record, instance)
          return if record.nil? || !we_can_set_the_inverse_on_this?(record)
          inverse_relationship = @reflection.polymorphic_inverse_of(record.class)
          unless inverse_relationship.nil?
            record.send(:"set_#{inverse_relationship.name}_target", instance)
          end
        end