docs: def update(self, command):
          """
          EXPECTING command == {"set":term, "clear":term, "where":where}
          THE set CLAUSE IS A DICT MAPPING NAMES TO VALUES
          THE where CLAUSE IS A JSON EXPRESSION FILTER
          """
          command = wrap(command)
          command_clear = listwrap(command["clear"])
          command_set = command.set.items()
          command_where = jx.get(command.where)
  
          for c in self.data:
              if command_where(c):
                  for k in command_clear:
                      c[k] = None
                  for k, v in command_set:
                      c[k] = v