code: def test_get_reason_phrase_default():
      rv = get_reason_phrase(1234)
      assert rv == "Unknown"
  
      rv = get_reason_phrase(1234, "Unknown error")
      assert rv == "Unknown error"
  
file_path: apiflask/tests/test_helpers.py
imports: import io
  import pytest
  from werkzeug.datastructures import FileStorage
  from apiflask import get_reason_phrase
  from apiflask import pagination_builder
  from apiflask import PaginationSchema
  from apiflask.helpers import get_filestorage_size
  from apiflask.helpers import parse_size
label_desc: Use image node_id 2 for calling a global function with example usage: test_get_reason_phrase_default() without return types