code: def test_uncomment():
      assert uncomment_line("# line one", "#") == "line one"
      assert uncomment_line("#line two", "#") == "line two"
      assert uncomment_line("#line two", "") == "#line two"
  
file_path: jupytext/tests/unit/test_header.py
imports: from nbformat.v4.nbbase import new_markdown_cell, new_notebook, new_raw_cell
  import jupytext
  from jupytext.compare import compare
  from jupytext.formats import get_format_implementation
  from jupytext.header import header_to_metadata_and_cell, metadata_and_cell_to_header, uncomment_line
label_desc: Use image node_id 1 for calling a global function with example usage: test_uncomment() without return types