code: def where(self, *custom_restrictions, **restrictions):
          
          for attr, value in restrictions.items():
              self.where_query[attr] = value
          if custom_restrictions:
              self.custom_where.append(tuple(custom_restrictions))
          return self
docs: Restricts the records to the query subject to the passed
          +restrictions+. Analog to "WHERE" in SQL. Can pass multiple
          restrictions, and can invoke this method multiple times per query.