code: def test_doc_api_similarity_match():
      doc = Doc(Vocab(), words=["a"])
      assert doc.similarity(doc[0]) == 1.0
      assert doc.similarity(doc.vocab["a"]) == 1.0
      doc2 = Doc(doc.vocab, words=["a", "b", "c"])
      with pytest.warns(UserWarning):
          assert doc.similarity(doc2[:1]) == 1.0
          assert doc.similarity(doc2) == 0.0
  
imports: import warnings
  import weakref
  import numpy
  import pytest
  from numpy.testing import assert_array_equal
  from thinc.api import NumpyOps, get_current_ops
  from spacy.attrs import DEP, ENT_IOB, ENT_TYPE, HEAD, IS_ALPHA, MORPH, POS, SENT_START, TAG
  from spacy.lang.en import English
  from spacy.lang.xx import MultiLanguage
  from spacy.language import Language
  from spacy.lexeme import Lexeme
  from spacy.tokens import Doc, Span, SpanGroup, Token
  from spacy.vocab import Vocab
  from .test_underscore import clean_underscore
label_desc: Use image node_id 20 for calling a global function with example usage: test_doc_api_similarity_match() without return types