docs: def _create_getters(self, klass):
          '''
          This method creates both the singular and plural getters for various
          Harvest object classes.
  
          '''
          flag_name = '_got_' + klass.element_name
          cache_name = '_' + klass.element_name
          setattr(self, cache_name, {})
          setattr(self, flag_name, False)
          cache = getattr(self, cache_name)
  
          def _get_item(id):
              if id in cache:
                  return cache[id]
              else:
                  url = '{}/{}'.format(klass.base_url, id)
                  item = self._get_element_values(url, klass.element_name).next()
                  item = klass(self, item)
                  cache[id] = item
                  return item
  
          setattr(self, klass.element_name, _get_item)
  
          def _get_items():
              if getattr(self, flag_name):
                  for item in cache.values():
                      yield item
              else:
                  for element in self._get_element_values(klass.base_url, klass.element_name):
                      item = klass(self, element)
                      cache[item.id] = item
                      yield item
  
                  setattr(self, flag_name, True)
  
          setattr(self, klass.plural_name, _get_items)