docs: def iterkeys(self, key_type=None, return_all_keys=False):
          """ Returns an iterator over the dictionary's keys.
              @param key_type if specified, iterator for a dictionary of this type will be used. 
                     Otherwise (if not specified) tuples containing all (multiple) keys
                     for this dictionary will be generated.
              @param return_all_keys if set to True - tuple of keys is retuned instead of a key of this type."""
          if(key_type is not None):
              the_key = str(key_type)
              if the_key in self.__dict__:
                  for key in self.__dict__[the_key].keys():
                      if return_all_keys:
                          yield self.__dict__[the_key][key]
                      else:
                          yield key            
          else:
              for keys in self.items_dict.keys():
                  yield keys