code: def test_default_button():
      button = Button("Exit")
      assert _to_text(button) == "<   Exit   >"
  
imports: from __future__ import annotations
  from prompt_toolkit.formatted_text import fragment_list_to_text
  from prompt_toolkit.layout import to_window
  from prompt_toolkit.widgets import Button
label_desc: Use image node_id 2 for calling a global function with example usage: test_default_button() without return types