code: def test_empty_strings():
      strings = StringStore()
      trees = EditTrees(strings)
      no_change = trees.add("xyz", "xyz")
      empty = trees.add("", "")
      assert no_change == empty
  
imports: import pickle
  import hypothesis.strategies
  import pytest
  from hypothesis import given
  from spacy import util
  from spacy.lang.en import English
  from spacy.language import Language
  from spacy.pipeline._edit_tree_internals.edit_trees import EditTrees
  from spacy.strings import StringStore
  from spacy.training import Example
  from spacy.util import make_tempdir
label_desc: Use image node_id 14 for calling a global function with example usage: test_empty_strings() without return types