code: def test_merge_sorted_one_empty() -> None:
      df1 = pl.DataFrame({"key": [1, 2, 3], "a": [1, 2, 3]})
      df2 = pl.DataFrame([], schema=df1.schema)
      out = df1.merge_sorted(df2, key="a")
      assert_frame_equal(out, df1)
      out = df2.merge_sorted(df1, key="a")
      assert_frame_equal(out, df1)
  
imports: from __future__ import annotations
  from datetime import date, datetime
  from typing import Any
  import pytest
  import polars
  from polars.testing import assert_frame_equal, assert_series_equal
label_desc: Use image node_id 22 for calling a global function with example usage: test_merge_sorted_one_empty() without return types