code: def test_group_by_category_str():
      assert helpers.group_by_category(["a", "a", "c", "b"]) == [
          0,
          0,
          1,
          2,
      ]
  
file_path: hypertools/tests/test_helpers.py
imports: import numpy
  import hypertools._shared.helpers
label_desc: Use image node_id 3 for calling a global function with example usage: test_group_by_category_str() without return types