docs: def init_default(self):
          """Overriden to take default database and save locally
  
          The issue was that init_default() sets self.filename to None; however there can be no
          SQLite database without a corresponding file (not using *memory* here)
  
          Should not keep default file open either (as it is in the API directory and shouldn't be
          messed by user)
          """
          import f311
          if self.default_filename is None:
              raise RuntimeError("Class '{}' has no default filename".format(self.__class__.__name__))
          fullpath = f311.get_default_data_path(self.default_filename, class_=self.__class__)
          self.load(fullpath)
          name, ext = os.path.splitext(self.default_filename)
          new = a99.new_filename(os.path.join("./", name), ext)
          self.save_as(new)