code: def test_is_dataclass() -> None:
      x0 = X(f0=0, f1=[1, 2, 3])
  
      assert dc.is_dataclass(x0) is True
      assert dc.is_dataclass(type(x0)) is False
      assert dc.is_dataclass(object()) is False
  
imports: from __future__ import annotations
  import pytest
  import bokeh.util.dataclasses
label_desc: Use image node_id 2 for calling a global function with example usage: test_is_dataclass() without return types