new_contents: from __future__ import unicode_literals
  
  from ...gold import biluo_tags_from_offsets
  from ...vocab import Vocab
  from ...tokens.doc import Doc
  
  import pytest
  
  
  @pytest.fixture
  def vocab():
      return Vocab()
  
  
  def test_U(vocab):
      orths_and_spaces = [('I', True), ('flew', True), ('to', True), ('London', False),
                          ('.', True)]
      doc = Doc(vocab, orths_and_spaces=orths_and_spaces)
      entities = [(len("I flew to "), len("I flew to London"), 'LOC')]
      tags = biluo_tags_from_offsets(doc, entities)
      assert tags == ['O', 'O', 'O', 'U-LOC', 'O']
  
  
  def test_BL(vocab):
      orths_and_spaces = [('I', True), ('flew', True), ('to', True), ('San', True),
                          ('Francisco', False), ('.', True)]
      doc = Doc(vocab, orths_and_spaces=orths_and_spaces)
      entities = [(len("I flew to "), len("I flew to San Francisco"), 'LOC')]
      tags = biluo_tags_from_offsets(doc, entities)
      assert tags == ['O', 'O', 'O', 'B-LOC', 'L-LOC', 'O']
  
  
  def test_BIL(vocab):
      orths_and_spaces = [('I', True), ('flew', True), ('to', True), ('San', True),
                          ('Francisco', True), ('Valley', False), ('.', True)]
      doc = Doc(vocab, orths_and_spaces=orths_and_spaces)
      entities = [(len("I flew to "), len("I flew to San Francisco Valley"), 'LOC')]
      tags = biluo_tags_from_offsets(doc, entities)
      assert tags == ['O', 'O', 'O', 'B-LOC', 'I-LOC', 'L-LOC', 'O']
  
  
  def test_misalign(vocab):
      orths_and_spaces = [('I', True), ('flew', True), ('to', True), ('San', True),
                          ('Francisco', True), ('Valley.', False)]
      doc = Doc(vocab, orths_and_spaces=orths_and_spaces)
      entities = [(len("I flew to "), len("I flew to San Francisco Valley"), 'LOC')]
      tags = biluo_tags_from_offsets(doc, entities)
      assert tags == ['O', 'O', 'O', '', '', '']
  
subject: Add tests for entity->biluo transformation