code: def test_monthly_returns():
      dates = [
          "31/12/2017",
          "5/1/2018",
          "9/1/2018",
          "13/1/2018",
          "17/1/2018",
          "21/1/2018",
          "25/1/2018",
          "29/1/2018",
          "2/2/2018",
          "6/2/2018",
          "10/2/2018",
          "14/2/2018",
          "18/2/2018",
          "22/2/2018",
          "26/2/2018",
          "1/5/2018",
          "5/5/2018",
          "9/5/2018",
          "13/5/2018",
          "17/5/2018",
          "21/5/2018",
          "25/5/2018",
          "29/5/2018",
          "2/6/2018",
          "6/6/2018",
          "10/6/2018",
          "14/6/2018",
          "18/6/2018",
          "22/6/2018",
          "26/6/2018",
      ]
  
      prices = [
          100,
          98,
          100,
          103,
          106,
          106,
          107,
          111,
          115,
          115,
          118,
          122,
          120,
          119,
          118,
          119,
          118,
          120,
          122,
          126,
          130,
          131,
          131,
          134,
          138,
          139,
          139,
          138,
          140,
          140,
      ]
  
      df1 = pd.DataFrame(
          prices,
          index=pd.to_datetime(dates, format="%d/%m/%Y"),
          columns=["Price"],
      )
  
      obj1 = ffn.PerformanceStats(df1["Price"])
  
      obj1.monthly_returns == df1["Price"].resample(
          "M"
      ).last().pct_change()
  
imports: import ffn
  import pandas
  import numpy
  from pytest import fixture
  from numpy.testing import assert_almost_equal
label_desc: Use image node_id 44 for calling a global function with example usage: test_monthly_returns() without return types