code: def test_None_conjunction(self) -> None:
      assert bus.nice_join(["one"], conjunction=None) == "one"
      assert (
          bus.nice_join(["one", "two"], conjunction=None) == "one, two"
      )
      assert (
          bus.nice_join(["one", "two", "three"], conjunction=None)
          == "one, two, three"
      )
      assert (
          bus.nice_join(
              ["one", "two", "three", "four"], conjunction=None
          )
          == "one, two, three, four"
      )
  
imports: from __future__ import annotations
  import pytest
  from urllib.parse import quote_plus
  import bokeh.util.strings
label_desc: Use image node_id 3 for calling the Test_nice_join obj's underlying member method code with example usage: obj.test_None_conjunction() without return types