def check_for_ar(schema, instance, key, value)
      if ar_collection?(instance, key)
        construct_collection(schema, instance, key, value)
      else
        call(value, instance.respond_to?(key) ? instance.send(key) : instance)
      end
    end
def check_for_ar(schema, instance, key, value)
      if ar_collection?(instance, key)
        construct_collection(schema, instance, key, value)
      else
        call(value, instance.respond_to?(key) ? instance.send(key) : instance)
      end
    end
Checks if result is an instance of ActiveRecord::Relation

 @param [Hash] schema the schema defined in the object's class.
 @param [Object] instance the instance of the object which methods from the schema are called on.
 @param [Symbol] key the symbol that represents method on the instance
 @param [Any] value returned when key is called on instance

 @return [Hash] the schema hash