code: def dropAllCollections(self):
          
          for graph_name in self.graphs:
              self.graphs[graph_name].delete()
          for collection_name in self.collections:
              # Collections whose name starts with '_' are system collections
              if not collection_name.startswith('_'):
                  self[collection_name].delete()
          return
docs: drops all public collections (graphs included) from the database