code: def test_get_parameters_keys_nested():
      tracker = SQLiteTracker(":memory:")
  
      to_insert = [
          dict(a=1, b=2),
          dict(a=dict(b=1, c=2), b=dict(c=2, d=3)),
          dict(a=dict(b=1, c=dict(d=2)), b=2),
      ]
  
      tracker.insert_many(to_insert)
  
      assert tracker.get_parameters_keys() == [
          "a",
          ("a", "b"),
          ("a", "c"),
          ("a", "c", "d"),
          "b",
          ("b", "c"),
          ("b", "d"),
      ]
  
imports: import json
  from uuid import uuid4
  import time
  import pytest
  from sklearn_evaluation.tracker import SQLiteTracker
  from sklearn_evaluation import tracker
  from sklearn_evaluation import plot
label_desc: Use image node_id 15 for calling a global function with example usage: test_get_parameters_keys_nested() without return types