contentBlock.characterList.reduce((characterList, character) => {

  const previousCharacter = characterList.last();

  if (character.entity.type === previousCharacter.entity.type
      && character.entity !== previousCharacter.entity) {

    Entity.mergeData(previousCharacter.entity, character.entity.end);

    return characterList.push(
      CharacterMetadata.applyEntity(character, previousCharacter.entity)
    );

  } else {

    return characterList.push(character);

  }

});