class_docstr: Tests for the `_downsample` private helper function.
class_docstr_tok: ["Tests","for","the","`","_downsample","`","private","helper","function","."]
code: def test_zero(self):
      xs = "abcdefg"
      actual = data_provider._downsample(xs, k=0)
      self.assertEqual(actual, [])
  
imports: import os
  import numpy
  from tensorboard import context
  from tensorboard.backend.event_processing import data_provider
  from tensorboard.backend.event_processing import plugin_event_multiplexer
  from tensorboard.compat.proto import summary_pb2
  from tensorboard.data import provider
  from tensorboard.plugins.graph import metadata
  from tensorboard.plugins.histogram import metadata
  from tensorboard.plugins.histogram import summary_v2
  from tensorboard.plugins.scalar import metadata
  from tensorboard.plugins.scalar import summary_v2
  from tensorboard.plugins.image import metadata
  from tensorboard.plugins.image import summary_v2
  from tensorboard.util import tensor_util
  import tensorflow.compat.v1
  import tensorflow.compat.v2
label_desc: Use image node_id 4 for calling the DownsampleTest obj's underlying member method code with example usage: obj.test_zero() without return types