code: def setUp(self):
      np.random.seed(1234)
      self.df = pd.DataFrame(
          {
              "x_batch_channel": list(range(10)),
              "y_batch_channel": np.random.random(10),
              "x_epoch_channel": list(range(5)) + [np.nan] * 5,
              "y_epoch_channel": np.random.random(10),
              "x_odd_channel": list(range(7)) + [np.nan] * 3,
              "y_odd_channel": np.random.random(10),
          }
      )
  
imports: import unittest
  import numpy
  import pandas
  from pandas.testing import assert_frame_equal
  from neptune.common.utils import align_channels_on_x, as_list, get_channel_name_stems, map_keys, map_values, merge_dataframes
  from tests.unit.neptune.legacy.random_utils import sort_df_by_columns
label_desc: Use image node_id 1 for calling the TestGetChannelNameStems obj's underlying member method code with example usage: obj.setUp() without return types