code: def is_valid_query(self, query):
          
          # No query, no item
          if not query:
              return False
          # Query is too short, no item
          if len(query) < self.get_query_size_min():
              return False
          return True
docs: Return True if the search query is valid.
  
          e.g.:
          * not empty,
          * not too short,