code: def test_missing_head_dep(en_vocab):
      """Check that the Doc constructor and Example.from_dict parse missing information the same"""
      heads = [1, 1, 1, 1, 2, None]  # element 5 is missing
      deps = [
          "",
          "ROOT",
          "dobj",
          "cc",
          "conj",
          None,
      ]  # element 0 and 5 are missing
      words = ["I", "like", "London", "and", "Berlin", "."]
      doc = Doc(en_vocab, words=words, heads=heads, deps=deps)
      pred_has_heads = [t.has_head() for t in doc]
      pred_has_deps = [t.has_dep() for t in doc]
      pred_heads = [t.head.i for t in doc]
      pred_deps = [t.dep_ for t in doc]
      pred_sent_starts = [t.is_sent_start for t in doc]
      assert pred_has_heads == [False, True, True, True, True, False]
      assert pred_has_deps == [False, True, True, True, True, False]
      assert pred_heads[1:5] == [1, 1, 1, 2]
      assert pred_deps[1:5] == ["ROOT", "dobj", "cc", "conj"]
      assert pred_sent_starts == [
          True,
          False,
          False,
          False,
          False,
          False,
      ]
      example = Example.from_dict(doc, {"heads": heads, "deps": deps})
      ref_has_heads = [t.has_head() for t in example.reference]
      ref_has_deps = [t.has_dep() for t in example.reference]
      ref_heads = [t.head.i for t in example.reference]
      ref_deps = [t.dep_ for t in example.reference]
      ref_sent_starts = [t.is_sent_start for t in example.reference]
      assert ref_has_heads == pred_has_heads
      assert ref_has_deps == pred_has_heads
      assert ref_heads == pred_heads
      assert ref_deps == pred_deps
      assert ref_sent_starts == pred_sent_starts
      # check that the aligned parse preserves the missing information
      aligned_heads, aligned_deps = example.get_aligned_parse(
          projectivize=True
      )
      assert aligned_deps[0] == ref_deps[0]
      assert aligned_heads[0] == ref_heads[0]
      assert aligned_deps[5] == ref_deps[5]
      assert aligned_heads[5] == ref_heads[5]
  
imports: import numpy
  import pytest
  from spacy.attrs import IS_ALPHA, IS_DIGIT, IS_LOWER, IS_PUNCT, IS_STOP, IS_TITLE
  from spacy.symbols import VERB
  from spacy.tokens import Doc
  from spacy.training import Example
  from spacy.vocab import Vocab
label_desc: Use image node_id 20 for calling a global function with example usage: test_missing_head_dep(en_vocab) without return types