code: def get_collection(cls, target=None):
  		
  		
  		if target is None:
  			if cls.__bound__ is None:
  				raise TypeError("Target required when document class not bound.")
  			
  			return cls.__bound__
  		
  		if isinstance(target, PyMongoCollection):
  			return target.with_options(**cls._collection_configuration())
  		
  		elif isinstance(target, Database):
  			return target.get_collection(cls.__collection__, **cls._collection_configuration())
  		
  		raise TypeError("Can not retrieve collection from: " + repr(target))
docs: Retrieve a properly configured collection object as configured by this document class.
  		
  		If given an existing collection, will instead call `collection.with_options`.
  		
  		http://api.mongodb.com/python/current/api/pymongo/database.html#pymongo.database.Database.get_collection