old_contents: 
  var servers = {
  	oldLocalHub: 'https://local.xena.ucsc.edu:7223',
  	localHub: 'http://127.0.0.1:7222',
  	publicHub: 'https://ucscpublic.xenahubs.net',
  	tcgaHub: 'https://tcga.xenahubs.net',
  	icgcHub: 'https://icgc.xenahubs.net',
  	toilHub: 'https://toil.xenahubs.net',
  	pcawgHub: 'https://pcawg.xenahubs.net',
  	singlecellHub: 'https://singlecell.xenahubs.net',
  	pancanAtlasHub: 'https://pancanatlas.xenahubs.net',
  	treehouseHub: 'https://xena.treehouse.gi.ucsc.edu:443',
  	gdcHub: "https://gdc.xenahubs.net",
  	atacSeqHub: "https://atacseq.xenahubs.net",
  	kidsFirstHub: "https://kidsfirst.xenahubs.net"
  };
  
  module.exports = {
  	servers,
  	serverNames: {
  		[servers.localHub]: "My computer hub",
  		[servers.publicHub]: 'UCSC Public Hub',
  		[servers.tcgaHub]: 'TCGA Hub',
  		[servers.icgcHub]: 'ICGC Hub',
  		[servers.toilHub]: 'UCSC Toil RNA-seq Recompute',
  		[servers.pcawgHub]: 'PCAWG Hub',
  		[servers.singlecellHub]: 'Single-cell RNAseq Hub',
  		[servers.pancanAtlasHub]: 'Pan-Cancer Atlas Hub',
  		[servers.treehouseHub]: 'Treehouse Hub',
  		[servers.gdcHub]: 'GDC Hub',
  		[servers.atacSeqHub]: 'ATAC-seq Hub',
  		[servers.kidsFirstHub]: 'Kids First Hub'
  	},
  	defaultServers: [
  		servers.localHub,
  		servers.publicHub,
  		servers.tcgaHub,
  		servers.pancanAtlasHub,
  		servers.icgcHub,
  		servers.pcawgHub,
  		servers.toilHub,
  		servers.treehouseHub,
  		servers.gdcHub,
  		servers.atacSeqHub,
  		servers.kidsFirstHub
  	],
  	enabledServers: [
  		servers.localHub,
  		servers.publicHub,
  		servers.tcgaHub,
  		servers.pancanAtlasHub,
  		servers.icgcHub,
  		servers.pcawgHub,
  		servers.toilHub,
  		servers.gdcHub,
  		servers.atacSeqHub,
  		servers.kidsFirstHub
  	],
  	publicServers: [
  		servers.publicHub,
  		servers.tcgaHub,
  		servers.icgcHub,
  		servers.toilHub,
  		servers.pancanAtlasHub,
  		servers.pcawgHub,
  		servers.treehouseHub,
  		servers.gdcHub,
  		servers.atacSeqHub,
  		servers.singlecellHub,
  		servers.kidsFirstHub,
  		'https://tdi.xenahubs.net',
  		'https://luad.xenahubs.net'
  	]
  };
  
new_contents: 
  var servers = {
  	oldLocalHub: 'https://local.xena.ucsc.edu:7223',
  	localHub: 'http://127.0.0.1:7222',
  	publicHub: 'https://ucscpublic.xenahubs.net',
  	tcgaHub: 'https://tcga.xenahubs.net',
  	icgcHub: 'https://icgc.xenahubs.net',
  	toilHub: 'https://toil.xenahubs.net',
  	pcawgHub: 'https://pcawg.xenahubs.net',
  	singlecellHub: 'https://singlecell.xenahubs.net',
  	pancanAtlasHub: 'https://pancanatlas.xenahubs.net',
  	treehouseHub: 'https://xena.treehouse.gi.ucsc.edu:443',
  	gdcHub: "https://gdc.xenahubs.net",
  	atacSeqHub: "https://atacseq.xenahubs.net",
  	kidsFirstHub: "https://kidsfirst.xenahubs.net"
  };
  
  module.exports = {
  	servers,
  	serverNames: {
  		[servers.localHub]: "My computer hub",
  		[servers.publicHub]: 'UCSC Public Hub',
  		[servers.tcgaHub]: 'TCGA Hub',
  		[servers.icgcHub]: 'ICGC Hub',
  		[servers.toilHub]: 'UCSC Toil RNA-seq Recompute',
  		[servers.pcawgHub]: 'PCAWG Hub',
  		[servers.singlecellHub]: 'Single-cell RNAseq Hub',
  		[servers.pancanAtlasHub]: 'Pan-Cancer Atlas Hub',
  		[servers.treehouseHub]: 'Treehouse Hub',
  		[servers.gdcHub]: 'GDC Hub',
  		[servers.atacSeqHub]: 'ATAC-seq Hub',
  		[servers.kidsFirstHub]: 'Kids First Hub'
  	},
  	defaultServers: [
  		servers.localHub,
  		servers.publicHub,
  		servers.tcgaHub,
  		servers.pancanAtlasHub,
  		servers.icgcHub,
  		servers.pcawgHub,
  		servers.toilHub,
  		servers.treehouseHub,
  		servers.gdcHub,
  		servers.atacSeqHub,
  		servers.kidsFirstHub
  	],
  	enabledServers: [
  		servers.localHub,
  		servers.publicHub,
  		servers.tcgaHub,
  		servers.pancanAtlasHub,
  		servers.icgcHub,
  		servers.pcawgHub,
  		servers.toilHub,
  		servers.gdcHub,
  		servers.atacSeqHub,
  		servers.kidsFirstHub
  	],
  	publicServers: [
  		servers.publicHub,
  		servers.tcgaHub,
  		servers.icgcHub,
  		servers.toilHub,
  		servers.pancanAtlasHub,
  		servers.pcawgHub,
  		servers.treehouseHub,
  		servers.gdcHub,
  		servers.atacSeqHub,
  		servers.singlecellHub,
  		servers.kidsFirstHub,
  		'https://tdi.xenahubs.net',
  		'https://luad.xenahubs.net',
  		'https://preview.xenahubs.net'
  	]
  };
  
subject: add a new preview data hub