code: def test_performance_stats(df):
      ps = ffn.PerformanceStats(df["AAPL"])
  
      num_stats = len(ps.stats.keys())
      num_unique_stats = len(ps.stats.keys().drop_duplicates())
      assert num_stats == num_unique_stats
  
imports: import ffn
  import pandas
  import numpy
  from pytest import fixture
  from numpy.testing import assert_almost_equal
label_desc: Use image node_id 41 for calling a global function with example usage: test_performance_stats(df) without return types