code: def update(self, document):
          
          if '_id' not in document:
              return self.insert(document)
  
          # Update the stored document, removing the id
          copy = document.copy()
          del copy['_id']
  
          self.db.execute("""
              update %s set data = ? where id = ?
          """ % self.name, (json.dumps(copy), document['_id']))
  
          return document
docs: Updates a document stored in this collection. If the document does not
          already have an '_id' value, it will be created