code: def fixed_freqs(self):
      return [
          "D",
          "H",
          "T",  # min
          "S",
          "L",  # ms
          "U",  # us
          # 'N' not supported
      ]
  
imports: import pandas
  import pyspark.pandas
  from pyspark.testing.pandasutils import PandasOnSparkTestCase, TestUtils
label_desc: Use image node_id 1 for calling the DatetimeIndexTestingFuncMixin obj's underlying member method code with example usage: obj.fixed_freqs() and returns: list