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// @see [Safari 10 supports complete ES2015 which includes Proper Tail Calls](https://medium.com/@dai_shi/safari-10-supports-complete-es2015-which-includes-proper-tail-calls-c8aee33db531)
function f(n, a) {
  'use strict';
  a = a || 1;
  return n == 1 ? a : f(n - 1, a * n);
}

f(1000000); // Safari: OK, Otherwise: Occurs stack level too deep

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// @see https://leetcode.com/problems/excel-sheet-column-title/description/
const V = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'.split('');

function fromNumber(n) {
  if (n < 1) throw new Error('`n` must be greater than 0');
  const v = (n, accum = '') => (
    n === 0 ? accum : v(
      Math.floor((n-1) / V.length),
      V[(n-1) % V.length] + accum
    )

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# @see https://docs.aws.amazon.com/ja_jp/AmazonCloudFront/latest/DeveloperGuide/LocationsOfEdgeServers.html
# @see https://morizyun.github.io/ruby/rails-controller-get-ip.html
# @see https://dev.classmethod.jp/cloud/aws/get-ec2-public-ip-range-by-powershell/
# @see https://github.com/rails/rails/blob/c81af6a/actionpack/lib/action_dispatch/middleware/remote_ip.rb#L112-L150
Rails.application.configure do
  ip_ranges_res = Faraday.get('https://ip-ranges.amazonaws.com/ip-ranges.json')
  ip_ranges = JSON.parse(ip_ranges_res.body)
  cloudfront_ips = ip_ranges['prefixes'].select { |v| v['service'] == 'CLOUDFRONT' }.map { |v| IPAddr.new(v['ip_prefix']) } +
                   ip_ranges['ipv6_prefixes'].select { |v| v['service'] == 'CLOUDFRONT' }.map { |v| IPAddr.new(v['ipv6_prefix']) }

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class ApplicationController < ActionController::Base
  private

  # @see [Rack::RequestでHTTPリクエストヘッダ一覧を書き出す - Qiita](https://qiita.com/mechamogera/items/9c620155e669b394d513)
  # @example
  #   {
  #     "Version"=>"HTTP/1.1",
  #     "Host"=>"localhost:3000",
  #     "User-Agent"=>"curl/7.54.0",
  #     "Accept"=>"*/*",

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type ActionTree<T> = {
  [ K in keyof T ]: {
    type: K;
    payload: T[K] extends { payload: any } ? T[K]['payload'] : never;
  };
};

type HogeActionTree = ActionTree<{
  'hoge/get': {
    payload: { id: string; };

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import Vue from 'vue';
import { ActionTree, MutationTree, GetterTree } from './type_helper';
import { cloneDeep } from 'lodash';

type Entity = {
  value: string
}

type EntityState = {
  records: Entity[];

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# for development
FROM fluent/fluentd as base

RUN gem install fluent-plugin-s3 -v 1.1.10 --no-document
RUN gem install fluent-plugin-cloudwatch-logs -v 0.7.3 --no-document


# for production
FROM base AS bundle

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# This logger is having the interface is same to `ActiveSupport::TaggedLogging`.
# @see https://github.com/rails/rails/blob/master/activesupport/lib/active_support/tagged_logging.rb
class JSONLogger < ActiveSupport::Logger
  class Formatter < ActiveSupport::Logger::SimpleFormatter
    def call severity, timestamp, progname, message
      JSON.generate({
                      type: severity,
                      time: timestamp.iso8601,
                      progname: progname,
                      message: message,

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import InvalidValueError from '~/lib/InvalidValueError';
import { PropertyHolder, isNullableType, isNotNullType } from '~/lib/typeHelpers';

export type Todo = {
  id: string | null;
  title: string;
  description: string;
};

export function fromObject(value: unknown): Todo {

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class FixHogeTables < ActiveRecord::Migration[5.1]
  def change
    table(:hoges).where(type: 'bar').each do |hoge|
      ...
    end
  end

  def table(name)
    result = Class.new(ActiveRecord::Base) do
      self.table_name = name