          new_index = self.c_add_aliases(alias_hash=alias_hash, entry_indices=entry_indices, probs=probs)
          self._alias_index[alias_hash] = new_index
  
          return alias_hash
  
      def append_alias(self, unicode alias, unicode entity, float prior_prob, ignore_warnings=False):
          """
          For an alias already existing in the KB, extend its potential entities with one more.
          Throw a warning if either the alias or the entity is unknown,
 
</s>
        if previous_alias_nr + 1 != self.get_size_aliases():
            raise RuntimeError(Errors.E891.format(alias=alias))
          new_index = self.c_add_aliases(alias_hash=alias_hash, entry_indices=entry_indices, probs=probs)
          self._alias_index[alias_hash] = new_index
  
        if previous_alias_nr + 1 != self.get_size_aliases():
            raise RuntimeError(Errors.E891.format(alias=alias))
          return alias_hash
  
      def append_alias(self, unicode alias, unicode entity, float prior_prob, ignore_warnings=False):
          """
          For an alias already existing in the KB, extend its potential entities with one more.
          Throw a warning if either the alias or the entity is unknown,
keep keep add keep keep keep keep keep keep
 avoid empty aliases and improve UX and docs (#6840)
spacy/kb.pyx