code: def _random_filename(self):
      choice_chars = string.ascii_letters + string.digits
      random_chars = [random.choice(choice_chars) for _ in range(10)]
      unique_filename = "Valid Folder " + "".join(random_chars)
      return unique_filename
  
file_path: plotly.py/packages/python/chart-studio/chart_studio/tests/test_plot_ly/test_file/test_file.py
imports: import random
  import string
  from chart_studio import plotly
  from chart_studio.exceptions import PlotlyRequestError
  from chart_studio.tests.utils import PlotlyTestCase
label_desc: Use image node_id 2 for calling the FolderAPITestCase obj's underlying member method code with example usage: obj._random_filename() and returns: unique_filename