text: from pymongo import MongoClient
  
  
  class Base(object):
  
      def __init__(self, args):
          self.uri = args.uri
          self.db_name = args.db_name
          self.client = MongoClient(self.uri)
          self.db = self.client[self.db_name]
          self._collections = None
  
      @property
      def collections(self):
      	return self._collections
      	
      @collections.setter
      def collections(self, _collections):
      	self._collections = {collection : self.db[collection]
                               for collection in _collections}
  
  