old_contents: 
  import pymongo
  
  connection = pymongo.MongoClient("mongodb://localhost")
  db = connection.vcf_explorer
  
  import database
  import parse_vcf
  import filter_vcf
  import query
  
new_contents: 
  import pymongo
  
  import config #config.py
  
  connection = pymongo.MongoClient(host=config.MONGODB_HOST, port=config.MONGODB_PORT)
  db = connection[config.MONGODB_NAME]
  
  import database
  import parse_vcf
  import filter_vcf
  import query
  
subject: Set mongodb settings using config.py