old_contents: exports.func = (client, oldUser, newUser) => {
  	if(!(oldUser.tag == newUser.tag)) {
  		client.guilds.reduce((list, guild) => {
  			guild.fetchMember(newUser)
  				.then((user) => {
  					client.logToGuild(guild, `:pen_ballpoint: ${client.formatUser(oldUser)} Tag was changed to \`${newUser.tag}\``);
  			}).catch((err) => { return; });
  		}, []);
  	}
  };
new_contents: exports.func = (client, oldUser, newUser) => {
  	if(!(oldUser.tag == newUser.tag)) {
  		client.guilds.reduce((list, guild) => {
  			guild.fetchMember(newUser)
  				.then((user) => {
  					client.logToGuild(guild, `:pen_ballpoint: ${client.formatUser(oldUser)} tag was changed to \`${newUser.tag}\``);
  			}).catch((err) => { return; });
  		}, []);
  	}
  };
subject: Tag -> tag in name change log (userUpdate event)