code: def _have_cache_for_date(self, dt):
          
          for p in self.projects:
              if self.cache.get(p, dt) is None:
                  return False
          return True
docs: Return True if we have cached data for all projects for the specified
          datetime. Return False otherwise.
  
          :param dt: datetime to find cache for
          :type dt: datetime.datetime
          :return: True if we have cache for all projects for this date, False
            otherwise
          :rtype: bool