class_docstr: Useful commands
  - run all tests: pytest examples/orderbook_data/example.py
  - run a single test:  pytest -s --pdb --disable-warnings examples/orderbook_data/example.py::TestClass::test_basic01
class_docstr_tok: ["Useful","commands","-","run","all","tests",":","pytest","examples\/orderbook_data\/example.py","-","run","a","single","test",":","pytest","-s","--","pdb","--","disable-warnings","examples\/orderbook_data\/example.py",":",":TestClass",":",":test_basic01"]
code: def test_exp_10(self):
      exprs = []
      names = []
      for i in [5, 10, 30, 60]:
          exprs.append(
              f'TResample(Ref(TResample($ask1 + $bid1, "1s", "ffill"), {-i}) / TResample($ask1 + $bid1, "1s", "ffill") - 1, "1min", "mean" )'
          )
          names.append(f"lag_{i}_change_rate" for i in [5, 10, 30, 60])
      df = D.features(self.stocks_list, fields=exprs, freq="ticks")
      df.columns = names
      print(df)
  
imports: from arctic.arctic import Arctic
  import qlib
  from qlib.data import D
  import unittest
label_desc: Use image node_id 22 for calling the TestClass obj's underlying member method code with example usage: obj.test_exp_10() without return types